NUTR 1030 1st Edition Lecture 11Outline of Last Lecture I. Identify LipoproteinsII. Understand the pathways through which cholesterol travelsIII. Recognize health risks of excess trans fatty acidsIV. Understand keys to prevention of high cholesterolV. Understand cardiovascular disease and how it is developedOutline of Current Lecture I. Understand protein functionsII. Identify the structure of proteins/amino acidsIII. Understand Transamination and DeaminationIV. Understand the production process of proteinsV. Recognize the digestion/absorption process of proteinsVI. Identify consequences of acute pancreatitisCurrent LectureProtein Functions:Protein ~14-16% of the body weight of heathy adultsProteins (amino acids) from diet are utilized for many body functions:- Building blocks of vital body components- Catalysis (enzymes)- Movement (contractile proteins)- Maintain fluid balance- Contribute to acid/base balanceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Immune function- Transport nutrients- Gluconeogenesis- Can also provide energyStructure of Protein:- Contains hydrogen, oxygen, carbon and nitrogen- Comprised of amino acids Nitrogen (amino) group Carboxyl (acid) group Hydrogen Side chain (R)- determines protein function and nameAmino Acids:- Nonessential (dispensable) amino acids (11 of them) Body can produce- Essential (indispensable) amino acids (9 of them) Must be taken in via food- Conditionally essential amino acids Essential during infancy, disease or traumaTransamination and Deamination:Transamination- Synthesis of non-essential amino acids Transfer of an amino group from an amino acid to a carbon skeleton to form a new amino acidDeamination- Breakdown of amino acids/amino group excretion Amino acid losing an amino group Amino group is incorporated into urea in the liver Excreted in urineProduction of Proteins:Synthesis of Proteins:- Amino acids are linked by peptide bonds to form proteins- Genes are sequences of DNA that specify protein structure- Synthesis of protein determined through gene expressionGene Expression:1. DNA unwinds from supercoiled shape (nucleus)2. DNA transcript phase (nucleus)- DNA code is transferred to messenger RNA (mRNA)3. mRNA translation phase- mRNA travels to cytosol- ribosomes read mRNA and translate instructions to form a specific protein4. Amino acids are strung together in sequence= protein- DNA-coded instructions determine shape, and thus function of proteins.Protein Organization:- Primary structure- order of amino acids determines shape- Secondary structure- weaker bonds between nearby amino acids form spiral-lie or pleated sheet shape- Tertiary structure- 3D folding determines- Quaternary structureFunctional Activity of Proteins:- Enzymes- Hormones- Structural proteins Contractile proteins (e.g. skeletal muscle) Fibrous proteins (e.g. connective tissue)- Immunoproteins- Transport proteins- Others (ex: glycoproteins, lipoproteins, proteoglycans)Additional “Roles”:Fluid balance- Responsible for oncotic pressure which brings fluid back from tissue into bloodstreamAcid/base balance- Amino acids are weak bases and can help regulate pHDenaturation and Adaptation:- Denaturation of proteins Altering protein’s 3 dimensional structure Acid, alkaline, heat, enzymes or agitation- Adaptation of protein synthesis Constant state of breakdown, rebuilding and repair (protein turnover) In response to diet, exercise, etc.Protein Digestion:- Stomach releases gastrin and stimulates: HCl production- denatures proteins Pepsin release- Cleaves protein chains into shorter pieces- Small intestine releases CCK and secretin Pancreas stimulated to release enzymes: trypsin, chymotrypsin, and carboxypeptidase- Cleave protein chains into peptides and amino acid Brush border peptidase enzymes break down remaining peptides into amino acidsTypes of Peptidases:- Usually cleave specific peptide bonds- 2 categories based on their site of cleavage Endopeptidases cleave internal peptide bonds Exopeptidases cleave external peptide bonds from N or C terminusN-Terminal:Met – Lys – Met – Val – Glu – Phe – Cys – Leu – His – Ile – Asn Acute Pancreatitis:- Obstruction of the duct secreting the digestive enzymes to the intestine- Enzymes act on the pancreas cells- Destruction of the pancreas cells- This condition is very painful and can be fatal is pancreas is destroyed.Absorption of Amino Acids (AA’s):- Active absorption- Peptides – AA’s- Peptide transport Most AA transported this way Rate for peptides > AA’s- Amino acid transport Many different systems Competition Redundancy Rate of EAA > NEAA- Absorbed AA’s –