Class 10-Proteins + A.A.

Mary Hendrickson , sept 30th

amino acids are made of xx, and these elements:

= building blocks of proteins

• cooH, amine group, H, and R group

• made of carbon, nitrogen, oxygen, sometimes sulphur

what are the conditionally essential AA?

Arginine

Cysteine

Glutamine

Glycine

Proline

Tyrosine

how does a protein become functional?

Several strands cluster together into a functioning unit

OR

A metal ion (mineral) or a Vit. join to the unit and activate it

primary, secondary, quaternary, and tertiary structures

structure of hemoglobin

what is proteome mean

A proteome is the entire set of proteins that is, or can be, expressed by a genome, cell, tissue, or organism at a certain time.

single gene disorders vs multi-gene disorders

Single-Gene Disorders

◦ Mutations inherited at birth (e.g., PKU, sickle cell,CF)

◦ Damage to the individual exerted early in life

Multigene Disorders: Chronic disease– eg CHD

◦ Influence of several genes

◦ Sensitive to interactions with the environment like pullustion, etc (risk factors)

◦ Single nucleotide polymorphisms (SNPs)

what is the key part about how inherited variations of AA sequence can negatively impact XXX of yyy

inherited variations of AA sequence can negatively impact FUNCTION of a PROTEIN

What is PKU

= Phenylketonuria

Non-functioning Phenylalanine Hydroxylase, can’t digest phenyl alanine AA

PHE is not hydroxylated to TYR

PHE builds up and is metabolized by alternate pathway to Phenylketones

Damages the developing brain

Neonatal screening programs

Medical Nutrition Therapy

◦ Keep PHE and phenylketones low

◦ TYR is an essential amino acid

What is cystic fibrosis

‘Every person has 2 copies of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. A person must inherit two copies of the CFTR gene that contain mutations — one copy from each parent — to have cystic fibrosis’

Poorly functioning chloride channel CFTR means:

◦ Thick mucus in lungs…infections – difficult to fix

◦ Pancreatic enzyme replacement…oral coated enzymes to facilitate digestion – easy to fix

*Medical Nutrition Therapy – the cornerstone of treatment for growth and immune

function

what is nutritional genomics

Nutritional genomics examines the interactions of genes and nutrients. These interactions include both nutrigenetics and nutrigenomics.

what is nutrigenetics

Nutrigenetics (or nutritional genetics) examines how genes influence the activities of nutrients.

what is nutrigenomics

Nutrigenomics, which includes epigenetics, examines how nutrients influence the activities of genos.

how do nutrients and phtyochemicals play a role in genetics?

what are some causes for protein denaturation?

Caused by:

• Agitation

• Heat

• Acid/Base

• Heavy metal salts

• Alcohol

• Digestion

• Radiation

Denaturatio

overview of overall protein ingestion

1. mouth: physical breakdown and moistening from chewing and saliva

2. stomach: HCL starts to denature and activates stomach enzymes

3. pancreas + small ints: enzymes from pancreas and small intestine split poly peptides further

4. small intestine: enzymes on surface of small intestine. hydrolyze peptides and now cells can absorb them 

2 main molecules regarding protein digestion in the STOMACH

1. HCL, hydrochloric acid= denatures protein strands, activates pepsinogen to pepsin

2. Pepsin= cleaves proteins to smaller polypeptides+some free AA , inhibits pepsinogen synthesis 

first couple steps of protein digestion in stomach in pancreas and small intestine (polypeptides to peptides)

1.Enteropeptidase (from intestinal brush border)

• Converts trypsinogen → trypsin (key master activator).

• Trypsin then activates procarboxypeptidases → carboxypeptidases and chymotrypsinogen → chymotrypsin.

• Also cleaves peptide bonds between lysine and arginine.

PANCREATIC PROTEASES (MADE IN PANCREAS BUT WORK IN SMALL INST.)

2.Chymotrypsin: cleaves bonds between Cuts after aromatic and bulky residues → Phe, Tyr, Trp, Met, Asn, His.

• Carboxypeptidases:  Cut amino acids from the C-terminal end 

• Elastase & Collagenase: Cleave  polypeptides into smaller peptides and tripeptides

second steps of protein digestion in small intestine (peptides to absorbed amino acids)

3. Enzymes on border of small inst. cells hydrolyze peptides so cells can absorb them 

• Intestinal Tripeptidases: Break tripeptides → dipeptides + amino acids.

• Intestinal Dipeptidases: Break dipeptides → amino acids.

• Intestinal Aminopeptidases: Chop amino acids off from the N-terminal end of oligopeptides

summary of proteins going through stomach then small intestine

how are single AA versus di/tri-peptides absorbed, where are they absorbed? 

once AA are absorbed through xxx, they are used by yy and zzz. once in zzz, they are transported to liver by the ——

Once absorbed through the intestinal cell walls, AA are either used by small intestines. or released into the bloodstream

- through blood, AA’s are transported to the Liver through the hepatic portal vein and used there

  OR

- Released into the blood to be taken up by other cells

◦ Cells can then link the amino acids together to make new proteins or use them as energy

!Body does not store excess amino acids!

explain AA competition in cell membranes

Unbalanced supplementation (like huge doses of one amino acid) can reduce absorption of others.

• Amino acids cannot diffuse freely across membranes.

• They need specific transporters (carrier proteins).

• Each transporter can carry multiple amino acids with similar size, charge, or structure.

• → This leads to competition: if two amino acids use the same transporter, they can interfere with each other’s absorption or uptake.

just a few out of the many roles of proteins in the body

1 Supporting Growth and Maintenance

2 Building Enzymes and Hormones

3 Building Antibodies

4 Maintaining Fluid and Electrolyte Balance

5 Maintaining Acid-Base Balance

6 Source of Energy

7 Blood clotting, etc

how do proteins support growth and maintenance? 

Amino acids must be continuously available for:

• Red blood cells

• Internal cell structures

• Muscles

• Intestinal cells

• Skin, hair, naills

all these AA are constantly being replaced!!

how are proteins involved in building enzymes and hormones

Enzymes= build substances, break them down,

or transform one substance into another (amino

acid into glucose) —> act as catalyst!!!

Hormones= Messenger molecules released by various glands in response to changes

ex:

• Insulin

• Glucagon• Serotonin(via tryptophan)

• Tyrosine used synthesize the chemical messengers

• epinephrine and norepinephrine

proteins are important for building antibodies because…

protein’s role in maintaining fluid and electrolyte balance

o Proteins attract water found in cells and in plasma

o Regulates the quantity of fluids and

dissolved particles in the compartments

of the body—> Water, sodium, potassium

BUT they Do not normally cross cell membranes,

when they do this causes problems for

the body like Fluid imbalance, e.g., edema

how are proteins important for maintaining acid-base balance 

o Blood proteins act as buffers to maintain a normal pH lvl (Blood pH is one of the most rigidly controlled conditions in body)

o Protect against acidosis (excess acid) and alkalosis (excessbase)

how can protein be a source of energy and glucose? what is gluconeogenesis? 

RDA=10-35% of total daily energy 

protein is xx% nitrogen

protein is 16% nitrogen

6.25g protein contains x grams of nitrogen

6.25g protein contains 1 gram of nitrogen

how to calculate nitrogen balance?

nitrogen balance= (N intake)-(Fecal N)- (Urinary N)

the three differnt types of nitrogen balance

what is deamination and synthesis of nonessential AA

• Definition: Removal of the amino group (–NH₂) from an amino acid.

• Where/why it happens:

  • Mainly in the liver.

  • Happens when amino acids are used for energy or when there’s excess protein.

• Process:

  • The amino group is removed → converted to ammonia (NH₃).

  • Ammonia is toxic, so it’s quickly converted into urea (via the urea cycle) and excreted in urine.

  • The remaining carbon skeleton (keto acid) can enter metabolism → used for ATP, glucose, or fat synthesis.

what coenzyme is required for transamination when the body transfers a NH2 from amino to a keto acid to form xxx

VITAMIN B6 is required for transamination when the body transfers a NH2 from amino to a keto acid to form NON-ESSENTIAL AA and new KETO ACID