ANSC 303 1st Edition Lecture 18Outline of Last Lecture I. Crude ProteinII. DigestionIII. Protein Digestion - Stomach A. HCL secretion B. PepsinIV. Protein Digestion - Small IntestineV. Pancreatic PeptidesA. Trypsin B. ChymotrypsinC. CarboxypeptidaseVI. Brush Border EnzymesA. AminopeptidaseB. DipeptidaseOutline of Current Lecture I. Trypsin InhibitorsII. Products of DigestionIII. Protein AbsorptionA. Whole Protein AbsorptionB. Protein AbsorptionC. Enterocytea. AA Absorptionb. Peptide Absorptionc. First CellsD. Basolateral MembraneIV. Ruminant Protein DigestionA. Sources AA to DuodenumB. MCP C. Rumen BacteriaD. Protein in the Dieta. Intake Protein b. NPNCurrent LectureThese 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.I. Trypsin Inhibitorsa. Small protein or peptides b. Present in plants, organs, and fluidsc. Inactivated by heatII. Products of Digestiona. Free AAb. Peptides i. Di ii. TriIII. Protein Absorptiona. Whole Protein Absorptioni. Occurs only in newborn 12 - 24 hoursii. Intact proteins engulfed by mucosal cellsiii. Allows absorption of antibodies from colostrum - IgGiv. Digestion of protein in stomach/small intestine discouragedv. Critical for livestock speciesb. Protein Absorptioni. AA, di-, tri-peptides absorbedii. Only free AA can enter the bloodiii. The AA and di and tri peptides need carriers to enter the enterocytec. Enterocytei. AA Absorption1. Absorbed by active and non-active transporta. AA dependentb. Active transport requires Na2. Carrier affinity a. Certain AA absorbed more quicklyi. Smallerii. Neutral iii. Essentialii. Peptide Absorption1. Majority of protein absorption2. More rapid than amino acids3. Coupled with Ha. Na and H exchange maintains gradient4. Metabolized intro free AA in the enterocytea. Peptidases come into play here5. Only free AA absorbed into the bloodiii. First Cells1. The cells are the first to see the AA2. Transport across the basolateral membrane 3. Protein synthesisa. Digestive enzymesb. Structure and growth4. Energy a. They like glutamineb. They will take all the glutamine5. Metabolized by the enterocyte:a. Aspartate b. Argininec. Methionined. Cysteined. Basolateral Membranei. Last barrier to absorption1. Leaves enterocyte2. Enters portal blood3. Portal blood leads to the liverii. Transport of free AA IV. Ruminant Protein Digestiona. Sources AA to Duodenumi. MCPii. UIPiii. Endogenous protein iv. Protein that enters duodenum differs from the dietb. MCP i. HQii. Highly digestibleiii. Microbial growth = supplyiv. Synthesized by NH3 and C chainv. Not always sufficient vi. Essential AA deficiency 1. Often during:a. Growth b. High productionc. Rumen Bacteriai. Dietary protein enters rumen ii. Proteolysis1. Determines available N, AA, peptides2. Influences MCP synthesisiii. Microbes fix NH3 to C chains1. C chains come from CHO d. Protein in the Dieti. Intake Protein1. Undegraded Intake Protein a. Escapes rumen fermentation b. Enters SI unaltered2. Degraded Intake Protein a. Available for microbesb. Altered by microbesii. NPN1. Non Protein Nitrogen 2. Urea3. Source of N only 4. No CHO