Download Module 1 - Proteins part B [1] Today we are going to talk about and

Module 1 – Proteins part B
[1]
Today we are going to talk about and conclude proteins part B. In proteins part B, we are going to stress
protein function, protein sources, and then go into this concept of protein quality. From previous
discussions dealing with macronutrients, we always focus on how much, or the quantity, of the nutrient. In
the case of proteins, it is not only how much, but is it the right stuff. So today let's continue by talking
about proteins part B.
[2]
Why do we need proteins? Why are they the third most important macronutrient? One of protein’s most
important functions is structural and body building. Muscle fibers are protein. Bone and teeth are
hydroxyapatite, which is protein, calcium, phosphorus, and water. So protein is a part of bone and teeth.
Elastin and collagen. Elastin we talked about with elasticity and the importance in the arteries. Collagen is
an important cementing agent for the cells. Your skin is protein, your hair is protein, and your nails are
protein. And you can draw a little arrow from your blood vessels back to elastin, again protein. So from a
structural, body integrity function, protein, as you can see, is very important.
[3]
Proteins function in regulation. Enzymes are proteins. All enzymes are proteins. What is the role of an
enzyme in the body for optimal health and well-being? They speed up chemical reactions. They make
reactions go a billion times faster than if you were to take the two reactants and put them together in a
test tube. They speed up immensely biochemical processes which help maintain optimal health and
well-being.
[4]
The diagram shows why enzymes work so well. There are a number of reasons why, but I’m only going to
go over two. The major reason is, enzymes are very specific for the chemical they are trying to break
down or convert. The enzyme has a very specific site of chemical activity for the chemical it is trying to
convert. This site is called the active site for the enzyme. The molecule it is trying to convert is called the
substrate. Think of the enzyme and substrate as puzzle pieces. The enzyme is one piece of the puzzle.
The substrate is the other piece of the puzzle and they fit exactly together. On the diagram, reaction B
shows a perfect fit between the enzyme and the substrate, the dipeptide. Two pieces of the puzzle fitting
exactly together is called enzyme specificity. Enzymes are made by the cells to process different
substrates. So enzymes can't do all things, they are very specific for certain families of compounds. If you
change the families of compounds slightly, you need a different enzyme to convert it or it will not break
down. In the example, these are peptidases, which take dipeptides and break them down into individual
amino acids. There are various types of peptidases, depending on what the dipeptide is. This is one of its
most important reasons why enzymes work so well and are so fast. They are very specific for a very
defined family of compounds. As you go through the reaction and you look at A, B, C, and then you get to
D, your products are formed. This brings us to our second point, and that is: after the whole process takes
place, the enzyme doesn't change. It doesn't change its shape or its function or its structure. It goes back
to where it started and looks for another dipeptide. So it is reusable. You don't have to make a new one,
or have a new one every time you want to break something down. It is a molecule that is very efficient at
what it does because of its specificity and the ability to not change after the reaction is completed. It goes
back to its original form and can start the reaction all over again. So you don't need to have new enzyme
for every molecule of substrate. You can actually have less and still get the job done.
[5]
This animation shows how specificity works for enzymes. Again, think about these as puzzle pieces, the
enzyme one part of the puzzle, the substrate the other part. The first substrate, the light purple, is larger
than the active site. The two puzzle pieces don't fit. The second substrate, the dark purple, is smaller and
will go into the active site, but it is not the right puzzle shape for the active site. The final substrate, the
red one, is of the right size and puzzle shape for the active site, which causes the enzyme to bind the
substrate and break the substrate down. This is how specificity works and why enzymes are efficient. You
will see this later on when we talk about digestion. We will talk about the hydrolysis reaction. You will see
that this reaction is the cornerstone for breaking down proteins, carbohydrates, and fats. However, each
of these require a different enzyme for this reaction to work. For proteins, they need proteases. For
carbohydrates, they need amylases. And for fats, they need lipases. Even though the reaction is the
same for all of these, you cannot use an amylase to break down protein, and vice versa.
[6]
Continuing on with proteins involved in regulation, certain hormones are proteins. Hormones regulate
actions. They control actions of the body. Insulin is one example. It regulates blood glucose. Thyroxine is
another example, from your thyroid gland. It regulates metabolic rate. Another regulation protein is
antibodies, which helps to defend against foreign substances; germs, bacteria, bad things. Your
antibodies are proteins.
[7]
Here’s an example of a macrophage. It was probably solicited by an antibody. There is a bacterium, the
yellow rod-like material, and the macrophage is coming out to get it. It will engulf and circle this bacteria
and it will digest it. That is how it gets rid of the foreign substance.
[8]
Other functions include acid-base balance. From part A of our discussion, we define proteins as been
made from amino acids. We remember that amino acids have a carboxyl group and an amino group, both
of these has acid and base properties. Proteins are energy source, as we have already mentioned. They
supply 4 kcal per gram of protein. The body prefers carbohydrates and fats for energy, and wants to
spare the protein. Is very costly to use protein for fuel. Protein is very expensive and it takes a lot more
energy and a lot more cost to produce good usable protein. Therefore, to use protein as an energy
source, you are throwing your money away. I would always say to you that if you pay attention to me, with
money I would save you, I could be driving around in BMWs, Mercedes, and Jaguars all day. It is
amazing the amount of money consumers pay for nothing. There are two groups that are prone to pay for
products that don't do them any good. You are one group, which purchases beauty aids, or things that will
make you look good and maintain your weight. It is estimated $15-20 billion are spent each year by your
age group on things that won't do you any good and have no benefit to you. The second group, I'm in the
second group, we are interested in extending life and minimizing the aging process, and they spend
about the same amount of money on products that won't do us any good. So know your facts as good
consumers, and you can save yourself a heck of a lot of money. Again, protein should be used for these
important functions, such as structural, regulatory, etc., while carbohydrates and fats should be used for
energy.
[9]
Some additional functions are osmotic pressure. Again, it does affect osmotic pressure and a symptom
you will see later on is edema in protein deficiency. In normal protein status, your blood pressure is
balanced by the counteracting force of protein. They are acids, bases, and they affect osmotic pressure.
For low-protein status, the blood pressure exceeds counteracting force of the protein, so your tissues get
swollen with fluids and you develop edema. This is very much a symptom associated with protein
deficiency. We will see this later on, when we talk about proteins and health and how these little kids look
like they are full and fat, but their bellies are empty and swollen.
[10]
Here is your favorite meal. What is the major nutrient in the meat? Hopefully, you won't be one of the 15%
that say something other than water. Water is the major nutrient in the meat.
[11]
In terms of protein, the third row from the top, you can see that this meal is a good source of protein. Your
percentage of calories from protein is a little higher than what we would like, and reflects the meal as high
in protein. The protein is mainly supplied by the meat, and possibly bacon bits. These are probably real
bacon bits for the time period. Today, they could be extruded plant material flavored with bacon, and may
not have as high a protein contribution.
[12]
Protein sources. You can see the percentage protein for various protein sources. Meat and fish are over
30%, cheeses are a little over 30%. Cottage cheese, a little less protein. Nuts are somewhere below 20%.
Eggs are around 15%. Cereal is 18%. Bread, legumes, and cooked cereals, as you can see, are mild
protein sources. Obviously, animal products are good protein sources, but plant products can also be a
good protein source as well.
[13]
What are the protein requirements for individuals? These requirements are important, so I would
remember them. For adults, it is 0.8 g per kilogram body weight. If you multiply that by the reference for
female, it comes out to be 46 g per day. And for the male, it comes out to be 58 g per day. Infants require
2.2 g per kilogram body weight. Why? Well, hopefully you said they are growing and developing, and that
is correct. Because they are growing and developing, they need additional protein in their diet.
[14] {[( This paragraph was on the original presentation, but did not play online )]}
{[( Now that we know our requirement, how much protein do we consume? The US average intake for
men is about 100 g/day, almost double. For women, it is about 70 g/day a little less than double. It is
more than we need in terms of optimal health and well-being. It again reflects are using protein for
energy because we have more than enough for its important functions. So give me the money you'll
save (ka ching) by eating too much protein so that I can buy my new BMW. )]}
[15]
Proteins in athletes. If you're going through rigorous athletic regimes, you may need anywhere from 1.2 to
1.8 g of protein per kilogram body weight, depending on what kind of exercises you are doing. However,
you should have no more than 5 to 10% above your normal requirements. Many athletes indulge highly in
protein. It is estimated that when you look at Olympic events, some Olympic athletes are eating pounds of
protein, which can be anywhere starting at 500 g of protein. It is well above what is considered normal,
well above what is considered needed for the athlete, and well above what may be considered safe,
probably putting themselves into harm’s way eventually.
[16]
To show you how fast you can accumulate protein in your diet, let us look at the following example. Just a
3 ounce hamburger with bun and 1 ounce of cheese, and a cup of milk will give you 42 g of protein. That
is very close to the women's requirement already, and not far away from the men's requirement of about
58 g. So you can pick up your protein requirement quickly, depending on the types of foods that you
consume.
[17]
Why do we need dietary protein? Protein is needed for cell breakdown and repair, and it is a part of our
structural tissue. Cells are the meaning of life, so keeping them happy keeps us happy. And protein is
necessary for cell integrity. Essential amino acids are needed in protein synthesis. If unavailable,
synthesis stops, and this is an important lead-in to why quality becomes an issue. Quality becomes an
issue because if the food does not supply us with adequate energy, or quantities of essential amino acids,
then we are really in trouble in terms of protein synthesis. Protein synthesis is an all-or-nothing event
here. If essential amino acids are unavailable, synthesis stops. If your cells say, “I need methionine”, an
essential amino acid, and you don't have enough in the pool of amino acids running in your cytoplasm,
synthesis stops. It will not continue, and it’s not going to substitute one amino acid for another. We offer
no substitutions here, and this is how it works: it stops. And if this was an important protein you may be in
trouble. So this is where quality becomes an issue, because if you don't get the essential amino acids
then you can't make all the proteins required for optimal health and well-being.
[18]
In terms of nutritional value, there are three definitions that define protein quality. In terms of protein
quality, the question that is asked: “How well does a food protein support protein synthesis, promote
growth, and maintain life?” This is where quality becomes the issue. How well does a food protein support
protein synthesis, promote growth, and maintain life? In my time, I remember commercials for peanut
butter that would say, “There is more protein in peanut butter than there is in a chicken or ham sandwich,”
or something like that. Looking at it from a quantity perspective, they are correct. They don't advertise
about the quality perspective, as to whether equal amounts the same protein will supply you with all the
essential amino acids, support protein synthesis, promote growth and maintain life like the chicken
sandwich. Now, quality becomes important. Is there a difference in usable protein between peanut butter
and that chicken sandwich? You bet.
[19]
Now that quality is an important issue for protein, there are three terms to categorize protein quality. The
first one is called a complete protein. It can promote growth and sustain life. It is complete, it has
everything. It contains an abundance of the essential amino acids in appropriate portions to promote all
protein synthesis. Almost all of your animal proteins are complete proteins. When broken down, they give
you an adequate supply of the eight or nine essential amino acids. Soy is somewhat of a question mark. It
is kind of right on the bubble, so that is why they put it as a question mark. It is not quite as good as the
animal proteins, but it is pretty close.
[20]
The next term is partially complete protein. These proteins are unable to promote growth, but may sustain
life. They are usually low in one or more essential amino acids. These are usually represented by
vegetable and cereal proteins. Because they are low in one or more of the essential amino acids, quality
becomes an issue. If you don't have all of the essential amino acids, you cannot make all the proteins
needed for growth and development. You probably can sustain yourself, but you are not at optimal health.
This type of protein is very real when it comes to certain types of protein deficiencies, disorders,
throughout the world.
[21]
The final term is incomplete protein. This protein is unable to maintain life or promote growth. The good
news is, there are very few of these, and gelatin is one example. Gelatin is innocuous. It is basically made
up of amino acids that you can manufacture yourself. It doesn't supply any of the eight essential amino
acids. As I said, most of the amino acids in gelatin you can make yourself. So the only useful thing for
gelatin is making Jell-O. Gelatin is the ingredient for Jell-O, and if you add an additional ingredient, vodka,
you have a Jell-O shooter. Because you're not going to get any protein kick out of it, you may get a vodka
kick out of it. If you try to sustain yourself on an incomplete protein, you will eventually go downhill and will
die. So, this concludes our discussion of proteins part B. Again, if you have the supplemental reading
book, we are on unit 15. Like before, if you have any questions please feel free to contact me and I will be
happy to answer them and help you in any way I can. Next time, our discussion will focus on the health
consequences of protein, mainly protein deficiencies, but we will also talk about any concerns dealing
with protein toxicity.