AssalamOAllaikum all!

I hope everybody is having the time of their life!

I'm studying the EDS in textual manner (not objective one) and creating the best possible number of MCQs from the topic under study myself. While studying vitamins and enzymes today it tickled the curiosity in me to know more about the same and that's what makes me seek your help here. I need the answers to the following few questions to end my curiosity.

Q1: Why certain enzymes require co-factors or co-enzymes to carry out their biological activity whereas protease, lipase or carbohydrase can take part in metabolic activities without any assistance?

Q2: Which organic compounds are most abundantly present in red blood cells of mammals?

Q3: Which co-factor or co-enzyme assists hemoglobin in oxygen-transport within the blood?

Q4: What amount of oxygen present in a sample of arterial blood of a healthy human is chemically combined with hemoglobin?

Q5: What is the main reason of vitamin loss?

Details of the above asked questions would prove more handy if you can kindly provide...
Thanks

Cooking and Nutrient Loss

While most animals thrive on diets consisting almost exclusively of raw, uncooked food, few human cultures have evolved or been sustained without incorporating some aspect of cooked food into their eating practices. At the World's Healthiest Foods, we encourage inclusion of both raw and cooked foods into the daily meal plan. We believe there is every reason to make the most from the nourishment available in both types of food.

The way that food is cooked is absolutely essential for avoiding unnecessary nutrient loss. Five minutes can make an enormous difference in the nutritional quality of a meal. (This is about the time it takes to walk away from the stove, answer the phone, and say that you can't talk right now because you are in the middle of cooking). In addition, every food is unique and should be treated that way when it comes to cooking temperatures and times. We refuse to simmer spinach for more than 2-3 minutes. But we know that kale needs to steam for 6-8 minutes. Head over to our Good Tasting Healthy Recipes to get all the details about each food and the unique cooking approach it deserves.

The traditional rules about heat, water, time, and nutrient loss are all true. The longer a food is exposed to heat, the greater the nutrient loss. Being submersed in hot water (boiling) creates more nutrient loss than steaming (surrounding with steam rather than water) if all other factors are equal. The lower nutrient loss from steaming is the main reason we recommend it so often in our recipes. We just can't think of any valid reason to expose a food to high heat and boiling water for any prolonged period of time, for example, more than twenty minutes. We even get our butternut squash steamed in that length of time!

With our very precise and short cooking times, you're unlikely to get a nutrient loss of more than 30% with most nutrients. In general, you're likely to get nutrient losses in the 5-15% range. This range is dramatically lower than the losses than occur in food processing, or in many cafeterias and restaurants where food is routinely overcooked (in Table 1, you will find a presentation of research results that have looked at how various cooking and preparation methods may impact nutrient loss from select foods). Processed foods often have nutrient losses in the 50-80% range - as much as ten times the amount that occurs with the World's Healthiest Cooking. The 5-15% nutrient loss that occurs with careful, minimized heat and water exposure is often a worthwhile loss, because it is accompanied by other changes in the food that can support out health. These other changes include improved digestibility, and the conversion of nutrients into forms that are more easily absorbed.

Table 1
Food Nutrient Method % Nutrient Loss
broccoli vitamin C blanch 47%
carrots folate boiling 79%
carrots beta-carotene canning 27%
cauliflower folate boiling 69%
grapefruit juice folate canning <5%
milk vitamin B12 boiling (2-5 minutes) 30%
mixed vegetables vitamin C blanching (3-5 minutes) 25%
mixed vegetables vitamin C boiling (10-20 minutes) 55%
mixed vegetables vitamin C canning 67%
mixed vegetables pantothenic acid canning 20-35%
mixed vegetables vitamin B6 canning 40-60%
navy beans calcium cooking 49%
navy beans copper cooking 59%
navy beans iron cooking 51%
navy beans magnesium cooking 65%
navy beans manganese cooking 60%
navy beans phosphorus cooking 65%
navy beans potassium cooking 64%
navy beans selenium cooking 50%
navy beans zinc cooking 50%
onions flavonoids boiling 30%
peanuts lysine cooking at 150ºF (90 minutes) 20%
peanuts lysine cooking at 150ºF (150 minutes) 40%
soybeans thiamin boiled 48-77%
spinach calcium blanching 0%
spinach flavonoids boiling 50%
spinach magnesium blanching 36%
spinach phosphorus blanching 36%
spinach potassium blanching 56%
tomato juice folate canning 70%
WHFoods

__________________
''Always bear in mind that your own resolution to succeed is more important than any one thing''

Hemoglobin/Oxygen Binding

The primary function of hemoglobin (Hb) is to transport oxygen. Since oxygen is not very soluble in water (the major constituent of blood), an oxygen transport protein must be used to allow oxygen to be 'soluble'. Hemoglobin (Hb) is the oxygen transport protein used in the blood of vertebrates. Below is a wireframe diagram of a hemoglobin molecule. It is composed of 4 polypeptide chains (represented in this diagram by different colors. Each chain contains one heme group (colored orange), each of which contains one iron ion (not shown). The iron is the site of oxygen binding; each iron can bind one O2 molecule thus each hemoglobin molecule is capable of binding a total to four (4) O2 molecules.

In humans, the average hemoglobin concentration is 16 g/100 ml. This means that there are approximately 150,500,000,000,000,000,000 hemoglobin molecules in 100 ml of whole blood. How many possible binding sites for oxygen are contained in 100 ml of blood? How many O2 molecules can be carried by 100 ml of blood if the hemoglobin is completely saturated (meaning every possible binding site is filled) with oxygen?

It is important that you remember that the purpose of Hb is to pickup oxygen at the lungs and to deliver it to the tissues. So Hb must be able to both bind and release oxygen and must be able to do these at the right places! You may want to think of this in regard to something that you understand such as the delivery of M&M's to Target stores. The M&M factory (here the lungs) produces M&M's (oxygen). In order to make money, the M&M's must be sold and one of the places that sells them are Target stores. Thus there must be a way to transport the M&M's to stores, including Target (the tissues). So, the M&M company has trucks (Hb) to deliver the M&M's. The trucks are completley filled at the M&M factory and then travel the highways and biways to the stores. When they arrive at the Target store, the truck unloads the M&M's and then returns back to the factory. Now, how many M&M's are delivered? It really depends on how many M&M's the store has sold since the last delivery. If, for example, no M&M's were sold, none would be delivered; if 10 boxes were sold, ten would be delivered. So, the amount of M&M's delivered depends on the amount of M&M's sold (used) by the store. This is the same with oxygen delivery to the tissues, Hb must be able to deliver more oxygen to those tissues that need more oxygen - tissues that use more oxygen need to have more oxygen delivered. Hb does this!
Oxygen Binding to Hemoglobin

The primary factor that determines how much oxygen is actually bound to hemoglobin is the partial pressure of oxygen (pO2) in the hemoglobin solution. For our purposes, only oxygen bound to Hb can be carried by blood. There is small amount that is dissolved in the plasma of the blood, however, this amount is physiologically insignificant and we will ignore it. This means that the maximum amount of oxygen that can be carried by blood is determined by the amount of Hb. When every oxygen binding site on all the Hb molecules are occupied by oxygen, the blood is said to be 100% saturated and the blood cannot carry any more oxygen. When half of the sites are filled with oxygen, the blood is said to be 50% saturated (I expect that you have the picture). The following graph demonstrates the effect that pO2 has on the percent saturation of Hb. This curve was created by a scientist who exposed Hb to different pO2 then determining the % saturation of Hb at each pO2.

How to read this graph:

To determine the % saturation of Hb at a given pO2, find the pO2 on X-axis and draw an imaginary line up until you reach the red curve. Then read the % saturation on the Y-axis. This has been done for you at two important points, a pO2 of 40 mm Hg (the pO2 that is normally at the capillaries in resting tissues) and a pO2 of 100 mm Hg (the pO2 that is normally in the capillaries in the lungs - this is constant and does not change under normal circumstances). Under normal circumstances, these are the only values that we must consider in a normal resting individual.

Find the arrow that originates from 100 mm Hg - you should be able to discover that the Hb will be about 97% saturated (which means that 97% of all oxygen binding sites will be occupied with oxygen) - just about 100 %. Since the pO2 of the capillaries in the lungs is 100 mm Hg (actually, it is a bit higher) , then the Hb in these capillaries will be almost completely saturated with oxygen. Since the pO2 of blood cannot change until the blood reaches the capillaries in the tissues, all arterial blood will be just about100% saturated and cannot not carry any more oxygen.

Now, find the arrow that originates from 40 mm Hg. At this partial pressure, the Hb is less saturated - about 70%. This is the typical pO2 in the capillaries of resting tissues. This means that the Hb in these capillaries are only 70% saturated. Since the blood entering these capillaries was 100% saturated (this blood is coming from the lungs) but is only 70% saturated when leaving the tissues. What happened to the other 30%? This oxygen was released from the Hb and is delivered to the tissues.

Now, imagine that the tissue is more active so that it is using more oxygen. This will mean that there is less oxygen (a lower partial pressure) in this tissue. Let us imagine that due to the increase use of oxygen by the tissue, the pO2 of the tissues is 30 mm Hg instead of the normal 40 mm Hg. If you check the graph, you will find that the % Hb saturation at this pO2 is about 61%. Since the blood entering these capillaries was 100% saturated (it is coming from the lungs) and is 61% saturated when leaving the tissues, the rest (39%) was released and delivered to the tissues. This is more oxygen then was delivered during normal conditions in which the pO2 is 40 mm Hg (remember the blood leaving the tissues in this case was about 70%, see above) which is what one would want to occur. If the tissue was so actve that the pO2 is ony 20 mm Hg, even more oxygen will be released - convince yourself that this is true by using the graph.

The bottom line is that Hb is made so that it will automatically deliver more oxygen to those tissues that are using more oxygen.

__________________
''Always bear in mind that your own resolution to succeed is more important than any one thing''

Hemoglobin (English pronunciation: /hiːməˈɡloʊbɪn/; also rendered as haemoglobin and abbreviated Hb or Hgb) is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates,[1] with the exception of the fish family Channichthyidae,[2] as well as the tissues of some invertebrates. Hemoglobin in the blood carries oxygen from the respiratory organs (lungs or gills) to the rest of the body (i.e., the tissues) where it releases the oxygen to burn nutrients to provide energy to power the functions of the organism, and collects the resultant carbon dioxide to bring it back to the respiratory organs to be dispensed from the organism.

In mammals, the protein makes up about 97% of the red blood cells' dry content, and around 35% of the total content (including water).[citation needed] Hemoglobin has an oxygen binding capacity of 1.34 ml O2 per gram of hemoglobin,[3] which increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in blood. The mammalian hemoglobin molecule can bind (carry) up to four oxygen molecules.[4]

Hemoglobin is involved in the transport of other gases: it carries some of the body's respiratory carbon dioxide (about 10% of the total) as carbaminohemoglobin, in which CO2 is bound to the globin protein. The molecule also carries the important regulatory molecule nitric oxide bound to a globin protein thiol group, releasing it at the same time as oxygen.[5]

Hemoglobin is also found outside red blood cells and their progenitor lines. Other cells that contain hemoglobin include the A9 dopaminergic neurons in the substantia nigra, macrophages, alveolar cells, and mesangial cells in the kidney. In these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidant and a regulator of iron metabolism.[6]

Hemoglobin and hemoglobin-like molecules are also found in many invertebrates, fungi, and plants. In these organisms, hemoglobins may carry oxygen, or they may act to transport and regulate other things such as carbon dioxide, nitric oxide, hydrogen sulfide and sulfide. A variant of the molecule, called leghemoglobin, is used to scavenge oxygen, to keep it from poisoning anaerobic systems, such as nitrogen-fixing nodules of leguminous plants.

__________________
''Always bear in mind that your own resolution to succeed is more important than any one thing''

Dinosaur Soft Tissue Found in T. rex Bones
by Rich Deem
Introduction

Previous studies of dinosaur fossils have indicated that organic material may be found in the femur (long leg bone) of certain dinosaurs (primarily Tyrannosaurus rex). The studies were limited to superficial morphological examination and rudimentary immunological analysis of some of the proteins. The results were, at best, equivocal. Certainly, some heme proteins (the protein that makes up hemoglobin found in red blood cells) or their breakdown products were found in the bones. The current study1 examines a newly discovered T. rex skeleton for the presence of intact soft tissue within the creature's femur (long leg bone).
New morphological study

The new study, published in the respected journal Science, revealed the presence of morphological objects that seem to be blood vessels (picture) with endothelial nuclei visible (picture), red blood cells, and osteocytes (bone cells, picture). Scientists removed the inner cortical bone from the femur and soaked it for 7 days in a solution of dilute acid to remove the surrounding bone. The resulting tissue (picture) was flexible and retained at least some cellular and subcellular structures. These structures were compared to those of modern ostriches, which were processed in a similar manner (except that the tissue needed to be chemically stained to visualize the tissue. Remarkably, nucleated red blood cells could be visualized within the blood vessels of the specimen. Both reptile and bird red blood cells possess nuclei in circulation, whereas mammalian red blood cells lose their nuclei prior to entering circulation.
Normal bone structure

Most kinds of vertebrates possess similar bone structure to allow for the growth of their skeletons as they mature. Bones are not solid structures, since to be so would require them to be far too heavy to enable efficient movement. The outer compact bone is largely solid, with only a few holes to allow blood vessels to enter and exit the inner part of the bone. The spongy inner bone is composed of a network of thin bone interspersed with blood vessels and marrow (which produces red and white blood cells). In a living animal, the inner spongy bone is moist tissue.
Normal fossilization

Normally, when an animal dies, its remains are scavenged and/or destroyed through decomposition. However, under rare circumstances (e.g., burial under sediment at the bottom of a lake, stream, river, or sea during a flood, or under sand during storms, or under ash during volcanic eruptions) animals can be preserved through rapid burial. After a period of time, the biological molecules of the organism are replaced by minerals which precipitate out of the water. The surrounding sediments are also turned to stone, thus encasing the fossil in stone. The skeleton in question was found in sandstone, a common mineral that is formed through this kind of process. In addition, the geology indicated that the area in which the fossil was buried was part of an estuary. It seems reasonable to conclude that the animal had died and was washed down into the sea, which had made up much of the current central portion of the United States.
Why was the soft tissue preserved?

Normally, following death, the remains are destroyed through scavenging and decomposition. However, during fossilization, hard materials are replaced with minerals. Normally, bacteria enter into the center of bones through breaks or through the holes through which blood vessels and nerves pass. The soft tissue is usually destroyed within a short period of time. In this instance, the soft tissue seems to have been preserved through dehydration and sealed from the presence of water and further decomposition. Contrary to the claims of some young earth creationists, the tissue is obviously not fresh, since it exhibits coloring that is not characteristic of fresh tissue. Fresh blood vessels and connective tissue are nearly transparent (except the blood cells themselves), which is why the ostrich tissue had to be chemically stained to produce the pictures used in the article. Another difference between the ostrich tissue and T. rex material was the requirement to use collagenase to release blood vessels from ostrich bone matrix. This fact indicates that much of the collagen from the T. rex sample was already degraded. The primary author indicated that the bones have a distinct odor, characteristic of "embalming fluids."2 Therefore, it is possible that the bones landed in some chemical stew that preserved the soft tissue inside from decomposition. For example, peat bogs produce chemicals that have preserved human bodies for thousands of years. It is likely that some similar rare process has preserved the soft tissue inside some T. rex bones.
"Tissue" contains little protein

Despite the appearance of being intact soft tissue, an analysis of fossil showed that it contained little intact protein. Whereas greater than 90% of the protein in living bone is collagen, ~1% was found in the medullary bone of the T. rex fossil.3 Multiple purification steps (solid-phase extraction, strong cation exchange, and reversed-phase microchromatography) were required in order to increase the protein content enough to perform mass spectrometry of the sample.4
Conclusion Top of page

The new study reveals that the cortical bone within T. rex femurs may, under certain conditions, retain cellular and subcellular details. Under normal conditions, fossilization replaces living material with minerals. In this case, the soft tissue was protected from degradation, possibly through some chemical process, then desiccated to prevent further changes. Upon treatment with water and dilute acid, the tissue was rehydrated, returning to an appearance similar to how it originally looked. Since no molecular studies have yet been done with the specimen, it is uncertain if the specimen contains original organic material or if the material was replaced by some mineralization or other chemical process. When more information is available, this page will be updated.

__________________
''Always bear in mind that your own resolution to succeed is more important than any one thing''

The above quoted part is the answer of my last question but insufficient one. Here is the detail...
The vitamin loss due to the exposure of the vitamins to heat is most particular to Vitamin C and Vitamin E which are sensitive to oxidation, especially when heated in contact with metals or alkali.
There are two categories of vitamins based on their solubility. The first set is the soluble vitamins which include Vitamin B Complex and Vitamin C. Other set is the fat (or lipid) soluble Vitamins which include Vitamin A, D, E and K. So vitamin loss due to boiling is most particular to B complex group which you have mentioned above.
As I have just read before logging in on the forum, the vitamin loss is usually due to their storage; i e vitamins cannot be kept for a longer period of time. That is the reason why we read on many supplement bottles "Extra/Excess vitamins have been added to make up the loss that occurs due to their storage".
Let's understand how vitamin loss can actually take place.
I'm going to detail you about same as follows:

Vitamin A: It is sensitive to oxygen and light. It means that too much of oxygen and light is essentially going to result in the loss of Vitamin A.
Vitamin D: There is usually very little loss of this vitamin. It is synthesized by ultraviolet radiations that we get from the sun. It is synthesized within the body itself. Humans don't have to this vitamin much.
Vitamin K: It is sensitive to acids, alkali, light and oxidizing agents.
Riboflavin: It is additionally sensitive to light. The loss of riboflavin can be caused due to boiling also as it is a water soluble vitamin ( i e it is a vitamin of B Complex group).

The rest of the detail shared in the same post is worthwhile too brother.



The above quoted part is the detailed answer of my question number three. So the co-factor or co-enzyme that assists hemoglobin in the oxygen-transport within the blood is HEME. It is the heme that binds oxygen with hemoglobin or takes up oxygen and releases it at right places. It also takes up Carbon Dioxide and releases it. In the above quoted bit of your post the answer of the question number four could have been given which I have just had a little earlier. The amount of oxygen present in a sample of arterial blood in a healthy human which is chemically combined with hemoglobin is about 98.5%. The other 1.5% is dissolved in the other blood liquids and not connected to the hemoglobin.
The other details given in the same post are a precious to my knowledge.


The above quoted part is the answer of Q2. Thanks for putting other relevant details.

Note: There is still one question that remains unanswered and that is the Q1.
Why co-factors are required by certain enzymes to carry out their biological activity whereas many enzymes like protease, carbohydrates, lipase etc can carry out metabolic activities without any assistance?

I've just got the answer to this question on internet a little while earlier.
Let us understand it here.
As we know that most enzymes are proteins (or nucleic acids). Some chemistry is not possible with amino acids/ nucleotide functional groups.
The reason why the chemistry is not possible is because certain amino acids are limited in their backbone structure ( i e limited in the number of r-group ).
Since it is not possible for all amino acids to chemically combine with certain enzymes, the enzymes therefore require co-factors or con-enzymes to loosely or tightly bind to them and thus assist in carrying out the perfect protein or enzyme activity.

Thanks for providing me such a great deal of information on the questions asked above. I will keep adding the relevant facts to this thread as I study further...

Regards

__________________
Real richness is that you are so expensive that no one can buy your character.

Adding some knowledge related to the question number 1 here.

Co-factor OR Co-enzyme:

Co-factor or co-enzyme is a non-protein chemical compound that is loosely or tightly bound to a protein required for the protein activity.
These proteins are commonly enzymes, and co-factors can be considered "helper molecules" that assist in biochemical transformation.
The enzymes that require co-factors for the complete biological activity are called Complex Enzymes.

More about co-factors:

• Not all vitamins are co-factors.

• All soluble vitamins with the exception of vitamin C are converted/ activated into co-factors.

In other words, B vitamins are converted or activated into co-factors.
Only vitamin K of the fat soluble vitamins is converted to a co-factor.

• Co-factors may also act as carriers of specific functional groups and acyl groups.

• Many vitamins are co-factors, or prosthetic group for enzymes.

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Real richness is that you are so expensive that no one can buy your character.

Co-factor Tree:



Co-factors can be divided into two groups as "Essential Ions" and "Co-enzymes".

• Essential ions which are loosely are further categorized into two kinds- activator ions (loosely bound to proteins) and metal ions also called metallo-enzymes (tightly bound to proteins).

• Co-enzymes are also further categorized in two kinds- co-substrates (loosely bound to the proteins) and prosthetic groups (tightly bound to proteins).

__________________
Real richness is that you are so expensive that no one can buy your character.

Here are some examples as how co-factors or co-enzymes assist in protein actitvities.

Oxygen-binding hemoglobin:

• A co-factor namely HEME is required here that takes up oxygen and carbon dioxide and release them at specific places within the body.

Chemical Capture of light:

• When a photon energy changes the covalent structure if protein a co-factor is required here to come and rescue from denaturation and bring it back to normal.

Electron Transfer Reactions:

• There are certain proteins/ nucleic acid radicals that are extremely dangerous for the body. In such situation poly aromatic/ conjugated enzymes or co-factors like NAD, FAD are taken assistance of by proteins or nucleic acids.

Note: We require co-factors or co-enzymes for the complete protein activity.
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Classes of co-enzymes:

• Co-substrates are altered during the reaction and regenerated by another enzyme.

• Prosthetic groups remain bound to the enzyme during the reaction and may be covalently or tightly bound to enzyme.

• Metabollite enzymes are synthesized by common metabollites.

• Vitamin-derived co-enzymes are derivatives of vitamins that need to be supplemented in food because they cannot be synthesized by mammals.

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Some knowledge about VITAMINS:

• First vitamin discovered was Thiamine B1.

• Not all vitamins are amines or nitrogen containing compounds.

• Vitamin requirements are usually expressed as RDAs (Recommended Dietary Allowance).

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Water Soluble Vitamins:

Thiamine (B1)

Riboflavin (B2)

Niacin (B3)

Pentothenic Acid (B5)

Pyridoxal (B6)

Biotin (B7)

Follic Acid (B9)

Cobalamin (B12)

Vitamin C

Lipid Soluble Vitamins:

Vitamin A

Vitamin D

Vitamin E

Vitamin K

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Real richness is that you are so expensive that no one can buy your character.