Chapter 6: protein and amino acids

PROTEIN DIGESTION: stomach - what acid denatures proteins - what enzyme breaks down strands of AA into polypeptides and single unit of AA - what is the role of the mucous lining in the stomach

- HCL - pepsin - protects the proteins from the stomach acid and digestive proteins

Equilibrium Nitrogen Balance

- Nitrogen in= nitrogen out - Equal amount of nitrogen in and nitrogen out. No extra or no lack of nitrogen in the body - Most common group- seen in a healthy college student, young retiree

Positive Nitrogen Balance

--more nitrogen is retained (for protein synthesis) than is excreted -Nitrogen intake > Nitrogen output -This means that an individual is taking in more nitrogen then they are letting out (sweating, peeing out) Example: -gaining body weight + repairing body -growth (infant, child, adolescence) -repair: eg. broken leg -pregnancy -ATHLETE TRAINING (only if addition LBM gained) • Examples: infants, children, pregnant women -Growing children need more protein, therefore more nitrogen in diet as they are growing new bone, and muscle cells to their bodies every day.

relationship between protein intake and kidney disease

-. A high protein intake increases the work of the kidneys, but it does not cause kidney disease. It may, however, accelerate kidney deterioration in people with chronic kidney disease lack of scientific evidence linking protein intake (1.5g/kg/day) and the initiation or progression of renal disease in healthy individuals

sickle cell anemia

-When abnormalities occur during protein synthesis. Hemoglobin becomes abnormal a change in the sequence of amino acids in hemoglobin alters the shape and function of the protein molecule sickle cell hemoglobins form long chains that distort the shape of red blood cells -blood clotting, stroke, severe pain, susceptible to infections, early death. People with this disease do not live long.

protein

-have an important amine group, which contains the chemical element nitrogen, while carbohydrates and fats do not.macronutrients: one of the energy-containing nutrients found in the diet and needed in large quantities; therefore, proteins are one of the macronutrients, -compounds composed of carbon hydrogen, oxygen, and nitrogen atoms arranged into amino acids linked in a chain. -have an important amine group, which contains the chemical element nitrogen, while carbohydrates and fats do not.

What is 'good quality' protein?

1. A protein that is well (completely) digested Animal protein 90-99% digested and absorbed Plant protein 70-90% most plants. Plant protein that is greater than 90% digested and absorbed is legumes, and soy protein. 2. Containing all AA in the right proportions for our body.

Functions of Proteins

1. Building materials for growth & maintenance: Proteins form integral parts of most body tissues and provide strength and shape to skin, tendons, membranes, muscles, organs, and bones. a. Collagen b. Replace dead cells 2. Enzymes 3. Hormones: Proteins regulate body processes. (Some, but not all, hormones are proteins.) 4. Regulators of fluid balance: Proteins help maintain the volume and composition of body fluids. a. Proteins attract water b. Usually within cells; leak out = edema 5. Acid/base regulators: Proteins help maintain the acid-base balance of body fluids by acting as buffers. a. Attract hydrogen ions b. Acids/alkaline denature protein 6. Antibodies: Proteins defend the body against disease and invading antigens by releasing antibodies 7. Transport vehicles: Proteins transport substances, such as lipids, vitamins, minerals, and oxygen, around the body. 8. Source of energy and glucose: Proteins provide some fuel, and glucose if needed, for the body's energy needs.

amino acid supplements: absorption and transportation issues

1. In GI Tract: -if too much of the amino acid (high concentration) could block receptors & overwhelm them. Since other AA use the same receptors, it could block them for being absorbed, causing AA imbalance A) Brain: to much PHE decreases absorption of TRP--> serotonin, decreased TRP cause moodiness -risk--> AA imbalance -absorption of short peptides v.s individual AA 2. N-retention --> we absorb di &tripeptides better than individual AA in GI tract -protein in food gives us better nitrogen retention (keeping N in the body) 3. expensive, taste bad, GIT distress -Bottom line: GET PROTEIN FROMO FOOD

protein structure

1. amino acids bind together to form polypeptides 2.polypeptide chains fold to form 3-dimensional shapes of a protein

protein digestion and absorption

1. from the MOUTH: chewing begins the mechanical break down of protein 2. starts in the STOMACH: HYDROCHLORIC denatures PROTEINS opening up their folded structure- more accessible to enzyme attack 3. enzyme PEPSIN (protein digesting enzyme) breaks and hydrolyzes proteins into POLYPEPTIDES and AMINO ACIDS -Pepsin is an enzyme that begins the digestion of protein in the stomach. -POLYPEPTIDES enter the SMALL INTESTINE and pancreatic (TRYPSIN and CHYMOTRYPSIN, pancreatic protein digesting enzyme) and intestinal proteases hydrolyze and break them down into smaller polypeptides, tripeptides, dipeptides and amino acids by (- Protase- enzyme from pancreas and small intestine that splits polypeptides--> tripeptides--> dipeptides--> single AA's.) -Protein digesting enzymes in the BRUSH BOARDER of the small intestine further break down the polypeptides 4. A variety of transport proteins move the products of protein digestion into the MUCOSAL CELL. Single amino acids, dipeptides, and tripeptides, can be absorbed in to the MUCOSAL CELL. Once inside they are broken down into single amino acids 6. amino acids pass from the mucosal cell into the BLOOD and travel to the LIVER, which regulates the distribution of amino acids to the rest of the body 7. Little dietary protein is lost in the feces

the liver: protein digestion and absorption

1. use amino acid for synthesis: required body protein 2.immediately used for Kcal by liver 3. conversion to access amino acid to glucose (glycogen) or amino acid to fat: VLDL to fat stores 4. rest: blood stream

protein functions

15% of body weight is protein. most is due to muscle protein

tri-peptide

3 amino acids linked by peptide bonds

tertiary structure of protein

3-D final shape of the protein

polypeptide

4+ more amino acids linked by peptide bonds

types of Protein Supplements

7. Protein Supplements ° Protein powders ° Whey protein ° Branched chain amino acids ° Amino acid supplements

protein-energy malnutrition (PEM)

A condition characterized by wasting and an increased susceptibility to infection that results from the long-term consumption of insufficient amounts of energy and protein to meet needs. e.g: KWASHIORKOR & MARASMUS

celiac disease: gluten intolerance

A disorder that causes damage to the intestines when the protein gluten is eaten. -eg. found in wheat, rye, barley, and other grains -gluten causes the body to attack the villi intestine, causing symptoms such as abdominal bloating and cramps, and anemia.

marasmus

A form of protein-energy malnutrition in which a deficiency of energy in the diet causes severe body wasting.

Kwashiorkor

A form of protein-energy malnutrition in which only protein is deficient.

what is protein quality?

A measure of how efficiently a protein in the diet can be used to make body proteins. 1.Digestibility of a protein 2. Types of Amino Acids (9 essential AA) 3. Are the amino acids in proportions to what we need in our bodies.

vegans

A pattern of food intake that eliminates all animal products.

vegetarianism

A pattern of food intake that eliminates some or all animal products.

Protein Recommendations: DRI values

AMDR: 10-35% Adults (19+)- 0.8 protein/kg/day

How do proteins provide energy?

All consumed protein MAY be used as energy Pro- digested amino acid- amino acid may be used for energy Takes a lot of energy- involves liver and kidneys.

Amino acid metabolism carbon skeleton functions

Amino acid metabolism carbon skeleton functions 1. converted amino acids to glucose 2. Entry energy producing pathways directly 3. Converted to fat and stored when we have everything we need

Amino Acid Metabolism

Amino acids enter from body tissue breakdown and from the diet into an amino acid 'pool' in a cell. 1. Synthesis of body proteins (enzymes, antibodies) 2. Deamination process of removing the amino group so you are left with free ammonia which is converted to urea, then urea gets sent to the kidneys for excretion into the urine.

structure of an amino acid

Amino group, Hydrogen, amino Acid group, and side chain

Phenylketonuria

An inherited disease in which the body cannot metabolize the amino acid phenylalanine. If the disease is untreated, toxic by-products called phenylketones accumulate in the blood and interfere with brain development. -phenylketone: which build up in the blood -children and infants high in phenylketone levels can interfere with brain development, causing intellectual disability

How do proteins help your immune defense?

Antibodies- fight invading microbes

how does protein act as Acid/base regulator?

By accepting and releasing hydrogen ions, proteins act as buffers, maintaining the acid-base balance of the blood and body fluids. acids-compounds that release hydrogen ions in a solution bases-compounds that accept hydrogen ions in a solution

Protein: What we need vs what we eat

CCHS: Canadians consume 15% kcal from protein DRI AMDR: 10-35% General N.A trend: At least sufficient, usually excess protein Who in N.A is at risk for adequate protein intake? People who are dieting and elderly women

• Eleven nonessential amino acids

Can be synthesized in the body from other amino acids or by adding nitrogen to carbon-containing structures

• Nine essential amino acids

Cannot be made by the body It is "essential" to obtain them from the diet/food

translation and transcription: protein synthesis

DNA in cell nuclei provides the information needed to assemble proteins -Protein Synthesis- involves DNA (messenger), mRNA, ribosomes, (transport) RNA - DNA- serves as the template to make mRNA - mRNA- has the instructions needed to make proteins. messenger RNA - Ribosomes- protein-making machinery of the cell, makes mRNA - tRNA, collects amino acids from the body pool/ cell fluid and brings them to the mRNA. transfer RNA - This all takes place to make proteins when we have enough AA present (in the pool). If there are not enough AA present then we cannot go through process properly 1. in the nucleus, the blueprint, or code, for the protein is copied or transcribed from the DNA gene into a molecule of messenger RNA (mRNA) 2. the mRNA takes the genetic information from the nucleus to structures called ribosomes in the cytosol, where proteins are made 3. in the cytosol, transfer RNA (tRNA) reads the genetic code and delivers the needed amino acids to the ribosome to form a polypeptide chain.

Gene

DNA segment that codes for specific protein A length of DNA that contains the information needed to synthesize a polypeptide chain; responsible for inherited traits.

protein recommendations:

DRI value: AMDR: 10-35% RDA: 0.8protein/kg/day (80 grams per day.): adults 19+ -0.8 g/kg body weight = 0.36 g/lb. Body weight

The human body is able to synthesize them

Lipids, carbohydrates, and proteins

PROTEIN SOURCES

Meat - 7 g / ounce Milk - 8 g/ cup Starch - 3 g/ serving Vegetable - 2 g/ serving Fruit - very little

How does protein help growth and repair of tissues?

Muscle protein eg. collagen structural role eg. actin/myosin- muscle contraction Normal body tissue "turnover" (breakdown and replacement)

protein requirements for athletes:

NON-ATHLETE: 0.8g/pro/kg body weight/day ENDURANCE: 1.2-1.4g/pro/kg/bodyweight/day POWER: 1.2-1.7g/pro/kg/bodyweight/day

protein requirements for

Needs vary with age/activity a. infants 6-12 mo 1.5 g /kg infants 12-36 mo 1.1 g /kg b. children 4-13 yo 0.95 g/kg c. children 14-18 0.85 g/kg d. pregnancy +25 g/ day e. lactation +25 g/ day f. athletes 1.2-1.7 g/kg g. illness/stress increases needs -Because the RDA meets the needs for replacing worn-out tissue, it increases for larger people; it also meets the needs for building new tissue during growth, so it increases for infants, children, adolescents, and pregnant and lactating women.

relationship between protein intake and body weight

Protein increases satiety to a greater extent, feelings of hunger are lower and feelings of fullness are higher on high-protein diets than CHO ° 30 g max at one time

incomplete dietary protein

Protein that is deficient in one or more essential amino acids relative to body needs. -plant proteins: low in one or more of the essential amino acids -soy protein which is a high-quality plant protein, is an exception to this generalization * Plants foods. • Gelatin

complete dietary protein

Protein that provides essential amino acids in the proportions needed to support protein synthesis. -animal proteins: easy to digest • Most animal foods. * Few grains: soy, amaranth, quinoa

Proteins Quality in Different Foods

Proteins from foods of animal origin- "complete" Proteins from foods of plant origin- "incomplete"

pregnancy and lactation

RDA: 25g of protein per day above the non pregnant recommendation

nitrogen intake --> Protein = nitrogen output

Results: Zero nitrogen balance -nitrogen intake=nitrogen output -total body protein does not change example: adult maintaining weight

how do proteins regulate body processes?

Some hormones e.g insulin and glucagon Enzyme trypsin, lactase, amylase Neurotransmitter e.g serotonin

nitrogen balance

The amount of nitrogen consumed in the diet compared with the amount excreted (N out) by the body over a given period. -Healthy adults should be in nitrogen balance • Amount of nitrogen consumed (in dietary protein) = amount excreted (in urine) macronutrients contain nitrogen: the amount of protein used by the body can be estimated by comparing nitrogen intake with nitrogen loss or output

gene expression

The events of protein synthesis in which the a cell converts the genetic code into RNA and protein. information coded in a gene is used to synthesize a product, either a protein or a molecule of RNA. process whereby the info coded in a gene is used to produce a product that functions in the body e.g glucagon: is a protein that is made in the pancreas. glucagon is not made by other body cells because the gene is not expressed in any other than those in the pancreas levels of nutrient also affects the expression of other genes

nutrigenomics

The study of how nutrition interacts with specific genes to influence a person's health the science of how nutrients affect the activities of genes

relationships between protein intake and bone loss

When protein intake is high, calcium excretion increases. Whether excess protein depletes the bones of their chief mineral may depend upon the adequacy of calcium in the diet. can cause Adult Bone Loss (Osteoporosis 1.5g/kg/day protein are associated with normal calcium

Di-peptide

When two amino acids join together to form one

Whey protein

a by-product of cheese production; falsely promoted as increasing muscle mass. Whey is the watery part of milk that separates from the curds. - popular among athletes hoping to achieve greater muscle gain

acidosis

above normal acidity in the blood and body fluids

alkalosis

above normal alkalinity in the blood and body fluids

amino acid pool

all of the amino acids in body tissues and fluids that are available for use by the body -provide energy- 4Kcal/g -occurs both when the diet contains protein in excess of needs and when the diet is low in energy -amino acid pool is used to synthesize body proteins and other nitrogen containing compounds

synthesis of nonprotein molecules

amino acids are needed for the synthesis of a variety of nonprotein molecules that contain NITROGEN eg. NEUROTRANSMITTERS: they transfer signals between the cells of the nervous system and can stimulate or inhibit a signal. e.g the amino acid tryptophan is used to synthesize the neurotransmitter serotonin, which promotes relaxation

what is produced when amino acids are deaminated?

ammonia is produced

hydration and kidney function

as protein intake increases above the amount needed, so does the production of protein breakdown products: UREA which much be eliminated from the body by the kidneys to do this: more water must be excreted in the urine, increasing water losses

lacto-vegetarian

avoid animal flesh and eggs but do consume some dairy products

protein from plants

bring poly and monounsaturated fats and dietary fibre -legumes: 15g of fibre per 240ml (1cup) -helps lower blood cholesterol -choosing nuts and seeds increase intake of heart healthy monounsaturated fats as well as fibre

amino acids

building blocks of proteins -every amino acid contains a NITROGEN

metabolic syndrome

constellation of 5 features: 1.abdominal obesity 2.increase fasting glucose 3.increase TG 4.decrease HDL 5.increase blood pressure

protein turnover

continuous synthesis and breakdown of body proteins: necessary for normal growth and maintenance of body tissues and for adaption to changing situations

How do proteins help transportation?

e.g hemoglobin- transports oxygen eg. transferin- blood transport protein for iron

heart disease and cancer risk

high protein diets are high in animal products (red meats and milk products): which is high in saturated fat, homocysteine, and cholesterol and low in fibre -protein-rich foods such as processed meat and red meat both will increases risk of heart disease and breast, colon, prostrate and pancreatic cancers,

9 essential amino acids

histidine isoleucine leucine lysine methionine phenylalanine threonine tryptophan valine

kidney stones

increase of urinary calcium excretion associated with high-protein has led to speculation that a high protein intake may increase the risk of _____ ______.

bone health

intake of both calcium and protein are adequate. High protein intake may increase the amount of calcium loss in the urine

primary structure of protein

linear order of amino acids in a chain

fluid balance

maintenance of the proper types and amounts of fluid in each compartment of the body fluids

why is nitrogen important in amino acids?

molecular building blocks of protein.

Negative Nitrogen Balance

more nitrogen is excreted than consumed (body proteins broken down) -Nitrogen intake < Nitrogen output This person is lacking nitrogen - Usually found in a malnourished person, an astronaut, surgery patient, ill patient Example: -Losing body weight -dieting (any) <--choice -wasting<-- not a choice -disease, burns -inactivity or weightlessness • Examples: starvation, serious injury, or illness

determine the grams of proteins required per day.

multiple weight in kilograms by the grams of protein per kilogram recommended for the specific gender and life-stage group Example: -23 yr old woman weighing 68kg would require 0.8/g/kg/day x 68 kg = 54.4 grams of protein/day

nutrient risks in vegetarian diets

nutrient deficiencies can be a problem people consuming supplemented vegetarian diets -contain little high-quality protein, are consumed by small and adults with increased protein needs, such as pregnant women and those recovering from illness or injury -vitamins and minerals: primary concern with vitamin B12 which is found in almost exclusively in animal products -zinc and iron: best source of this is from red meats and are poorly absorbed in plant foods -low intakes of omega-3 fatty acids including EPA and DHA

Acids/alkaline denature protein

outside blood's acid-base ph balance

enzymes

proteins that facilitate chemical reactions without being changed in the process; protein catalysts break down substances, but they also build substances (such as bone) and transform one substance into another (amino acids into glucose

deamination

removal of the amino (NH2) group from a compound such as an amino acid to product ammonia it is the product when amino acids are broken down

genomics

study and comparison of genomes within a single species or among different species

protein and amino supplements

supplements will only impact these only if the diet is deficient in protein in the first place.

matrix

the basic substance that give form to a developing structure; in the body, the formative cells from which teeth and bones grow

denaturation

the change in a protein's shape and consequent loss of its function brought about by heat, agitation, acid, base, alcohol, heavy metals, or other agents.

peptide bond

the connection between adjacent amino acids

Limiting amino acid

the essential amino acid that is available in the lowest concentration in relation to the body's needs -within protein synthesis a shortage of one amino acid will stop the process. -if the missing amino acid is a nonessential amino acid it can be synthesized in the body and protein synthesis can continue

branched chain amino acids

the essential amino acids leucine, isoleucine, and valine, which are present in large amounts in skeletal muscle tissue; falsely promoted as fuel for exercising muscles used in dietary supplements for athletes

transcription

the process of copying the information in DNA to a molecule of mRNA

translation

the process of translating the mRNA code into the amino acid sequence of a polypeptide chain

collagen

the protein from which connective tissues such as scars, tendons, ligaments, and the foundations of bones and teeth are made.

what determines a final protein and its function?

the shape determines the function of the protein -amino acid sequence of a protein that determines its final 3D shape - a protein shape is critical to its function e.g. the elongated shape of the connective tissue proteins, collagen and alpha keratin, allows them to give strength to finger nails and ligaments e.g. hemoglobin: oxygen carrying protein has a spherical shape which allows proper functioning of the red blood cells

edema

the swelling of body tissue caused by excessive amounts of fluid in the interstitial spaces, seen in protein deficiency (among other conditions)

to determine Protein requirement:

to determine body weight. if weight is measured in pounds, covert to kilograms by dividing by 2.2. weight in lbs/2.2 lbs = weight in kg for example: 150lbs/2.2 lbs= 68 kg

complementary proteins

two or more dietary proteins whose amino acid assortments complement each other in such a way that essential amino acids missing from one are supplied by the other -ex: rice (met + cys) and beans (lys) -• Complementary proteins do not need to be eaten in the same meal, only the same day -many vegetarians improve the quality of proteins in their diets by combining plant-protein foods that have different but complementary amino acid patterns

types of vegetarian diets

vegan, lacto-vegetarians, lacto-ovo-vegetarians

lacto-ovo-vegetarian

who eat no animal meat but do eat eggs and dairy products such as milk and cheese