Lectures 2 2010

Lectures 2 2010 - Biochemistry II Amino Acid Catabolism...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Amino Acid Catabolism Biochemistry II Learning Objectives • First step in amino acid degradation is removal of the α -amino group. • The α -amino group of many a.a. is transferred to α - ketoglutrate (catalyzed by aminotransferases = transaminases) to form glutamate Glutamate is oxidatively deaminated to form NH 4 Alanine Cycle (Muscle to Liver); Glutamine Fate of NH 4 and the Urea Cycle • The remaining Carbon skeleton ( α -ketoacid ) of a.a emerges as a major metabolic intermediates
Background image of page 1

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

View Full DocumentRight Arrow Icon
There is no storage form of Amino Acids, therefore excess needs to be converted to other forms; to be used as energy or stored as glycogen/fat. C H 3 N + CH O O - R Disposal of Nitrogen Atom (Urea) Recycling of the Carbon Skeleton Amino Acid Breakdown Amino acids Breakdown - When aa are plentiful or CH 2 O unavailable…. - during normal degradation (= turnover) of cellular protein - when diet rich in protein - during starvation or diabetes, when CH 2 O not available as fuel - aa lose their amino groups, forming…. α -keto acids - can be: 1. oxidized to CO 2 + H 2 O 2. provide 3- and 4-carbon units that can be converted to Glc as fuel NH 4 + - can be: 1. recycled 2. excreted as: NH 4 + urea uric acid - Glutamate plays a key role…. C H 3 N + CH O O - R
Background image of page 2
Transfer of α -amino groups to α -ketoglutarate - In transamination reactions catalyzed by aminotransferases - α -amino groups of aa are transferred to the α carbon of α -ketoglutarate forming glutamate - Different aminotransferases , with speciFcity for different aa - Aminotransferases all have the same mechanism and use a specialized carrier of amino groups = pyridoxal phosphate ( PLP ) α -ketoglutarate Aminotransferase B6 Flow of Nitrogen: In tissues (e.g Muscle), most amino acids transfer their α -amino group to α -ketoglutarate to form Glutamate
Background image of page 3

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

View Full DocumentRight Arrow Icon
Aminotransferase The Aminno group is then transferred from Glutamate to Pyruvate, producing Alanine. Pyruvate α -ketoglutarate Aminotransferase α -ketoglutarate Glutamate
Background image of page 4
During amino acid breakdown, the α -amino Nitrogen gets incorporated as the α -amino group in Alanine or the amide group in Glutamine.
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/16/2010 for the course BIO 362 taught by Professor Walikarzai during the Spring '10 term at SUNY Stony Brook.

Page1 / 22

Lectures 2 2010 - Biochemistry II Amino Acid Catabolism...

This preview shows document pages 1 - 6. Sign up to view the full document.

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