Chapter 7- PROTEINS

how much energy from protein

4kcals/g

amino acids

building blocks of protein

protein components

Carbon

Hydrogen

Oxygen

NITROGEN

"R" group of amino acids

determines:

-Structure

-Function

-Name

essential amino acid

must come from diet, body cannot produce

PHENYLKETONURIA (PKU)

-Missing the enzyme that converts amino acid phenylalanine (essential) into amino acid tyrosine (non-essential)

-Phenylalanine builds up in the blood

-Tyrosine is deficient

vitamin b6 functions

-Coenzyme in more than 100 enzymatic reactions

-Amino acid metabolism for transamination (move N-containing group)

-Converts essential amino acids to non-essential amino acids

-Required for the release of glucose from glycogen

-Helps in inflammation regulation

-Required for folate metabolism

-Involved in neurotransmitter synthesis

protein synthesis

-Individual amino acids are linked together

-Peptide bond

-Make chains of 2-2000 amino acids long

sickle cell anemia

-Consequence of errors in protein coding and building

-Red blood cell is misshapen,Abnormal crescent (sickle)

-Decrease in biological function, Cannot carry oxygen as efficiently

primary structure of protein

amino acid chain

secondary structure of protein

interaction among amino acids and side chains, causing chains to bend

tertiary structure of protein

protein folds into 3D shape

quaternary structure of protein

more than one protein shape linked together

protein denaturation

-Unwinding & unfolding of tertiary structure

-Acid or base solutions, enzymes, heat, agitation

-Destroys biological function

protein digestion

GOAL: denature proteins and breakdown to amino acids

digestion in stomach

-Enzymatic digestion

-Hydrochloric acid

-Long polypeptides (proteins) to shorter chains

digestion in small intestine

-When chyme arrives - stimulates release of pancreatic and intestinal enzymes

-Pepsin/pepsinogen

-Polypeptides → shorter peptides and amino acids

protein function

-Produce vital body structures

-Maintaining fluid balance

-Contributing to acid-base balance

-Forming hormones, enzymes and neurotransmitters

-Contributing to immune function

-Transporting nutrients

-Forming glucose

-Providing energy

Gluconeogenesis

producing glucose from specific amino acids

glycolysis

-break down carbohydrates to eventually generate energy

-glucose → 2 pyruvate

SYNTHESIS OF ACETYL-COA

-1 molecule of 3-carbon pyruvate → 1 molecule of 2-carbon acetyl CoA

transferring electrons

-Electrons are transferred from energy yielding compounds (food) to produce ATP (energy)

-Achieved through removing electrons from energy yielding compounds (oxidized) and adding it to a new compounds (reduced)

thiamin

-Vitamin B1, water soluble

-Coenzyme for metabolism of carbohydrates and certain amino acids

PANTOTHENIC ACID

-Vitamin B5, water soluble, "from every side"

-Formation of acetyl Co-A required for molecules to enter the citric acid cycle

--Carbohydrates, fat, protein and alcohol

-Formation of coenzyme A (CoA) required for energy metabolism

biotin

-Vitamin B7, water soluble, "egg white injury"

-Coenzymes in reactions

-Add carbon dioxide involved in carbohydrate, fat and protein metabolism

-Breakdown of some amino acids

-Bind proteins that help DNA fold

citric acid cycle

Series of chemical reactions that cells use to convert carbons from acetyl coA → Carbon Dioxide (CO2)

riboflavin

-Vitamin B2, water soluble, "yellow enzyme"

-Component of 2 coenzymes in energy metabolism

-Electron acceptors and donors

-FAD →→ FADH2

-Activate other B vitamins

-Antioxidant function

niacin

-Vitamin B3, water soluble

-Coenzyme in energy metabolism

-Electron acceptor and donator

-NAD → → NADH

protein needs

-Average need: 0.8 g/kg/bw

-Can be increased during illness, injury, highly trained athletes

protein quality

Food protein's ability to support body growth and maintenance

complete protein

contain all 9 essential amino acids

incomplete protein

missing 1 or more essential amino acid

Digestibility

how efficiently absorbed protein is converted into body tissue protein

complementary proteins

2 incomplete protein foods combined = a complete protein food

effects of high protein diets

Overburden the kidneys

Dehydration

May increase health and disease risk

May cause loss of bone mass

health advantages of vegetarian diet

Antioxidants (vitamins, minerals, phytochemicals)

High in fiber

Lower in saturated fat & cholesterol

May lower blood cholesterol, LDL

Lower risk of hypertension, heart disease, cancer, type 2 diabetes, obesity