Lecture 07 - Protein and Nucleic Acid

Lecture 07 - Protein and Nucleic Acid - L ecture 07...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 07 – Protein/Nucleic Acid Protein assimilation ( general features ) Many similarities to carbohydrate assimilation Both are water soluble monomers Luminal digestion to oligopeptides with limited digestion to free AA The challenge is to get them through the cell membrane they like it in the lumen Brush border digestion to yield tri- and dipeptides and free amino acids Unlike Carbohydrate that we can only take up monomers With AA we can take up tri and di and free AAs (oligopeptides can be absorb) Cytosolic digestion (the third and final phase) There are 20 AAs (much more diverse than carbohydrates) Differs from carbohydrate absorption in that: Oligomers can be transported into enterocyte Cytosolic digestion occurs Greater diversity of substrates and products requires many more peptidases and transporters Nutritionally-important amino acids Amino acids in yellow are essential AAs (they must be obtained) Cannot make de novo or convert from other AAs Complete vs incomplete dietary protein People who follow a vegetarian diet (have to combine different vegetables you would get all your essential amino acids, but if you’re vegan you may become deficient in the essentials AA Protein assimilation (1- gastric proteolysis ) - The first step occurs in the stomach Mediated by pepsins Stored and secreted by chief cells as inactive precursors Autocatalytic cleavage of N-terminal peptide yields active form at acid pH Cleave at neutral amino acids – preference for large aliphatic and aromatic The overall effect is to produce large not absorbable peptides (it
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

Lecture 07 - Protein and Nucleic Acid - L ecture 07...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online