Protein metabolism by abrar khan

BY

ABRAR KHAN

St of Post RNBSCN

Define Protein and discuss the bio medical importance of protein.

What are Amino acid and list the essential and non essential protein.

Discuss the concept of general amino acid pool and how it is formed?

Study the sources and utilization of amino acid

Define Nitrogen balance.

Define Transamination ,site of transamination,enzyme involve in this and discuss the clinical significance.

Study about the deamination and types of this

Define Transdeamination.

Discuss the Urea formation and clinical significance.

Greek word meaning .Primarily or holding first place.

Proteins are the main structural components of the body

They are nitrogenous macromolecules composed of many aminoacids.I n addition to C,H,&O protein also contain N.

Replacing Nitrogen of the body.

Biochemical catalyst known as enzymes are P

Proteins known as immunoglobulin.

Several hormones are protein in nature.

Carry out mechanical support.

Transporting specific substances.

Supplying energy .

Maintain electrolyte and water balance.

Amino acid is the smallest unit of protein and is an organic molecule made up of amine and carboxylic acid functional groups. An amino acid is composed of nitrogen, carbon, oxygen, and hydrogen molecules.

About twenty amino acids have been named and 8 of these are described Essential Amino acid because they cannot be synthesized in the body

The remainder are described as non-essential amino acids b/c they can be synthesized by many tissues.

The entire collection of free amino acids in the body is known as amino acid pool

SOURCES OF AMINOACID EXOGENOUS: derived from dietary protein Endogenous:

Tissue breakdown Synthesized by transamination

non –essential amino acid.

Tissue amino acid.

Plasma protein formation.

Formation of globin of Hb.

Formation of protein hormones and neurotransmitters.

Protein of milk

Formation of glucose

Energy production

NH3 and urea formation.

The term "nitrogen balance" refers to the amount of nitrogen the body excretes, as opposed to the amount of nitrogen the body takes in.

Transfer of amino group from an amino acid to keto acid is known as transamination.

General Process of transamination..Site of Transmination: Principally take place in

liver,kidney,heart and brain..Enzyme concerned in transamination are

transaminases.Clinical Significance:Alanine aminotransferase (ALT)

and aspartate aminotransferase (AST) are the two most common human transaminases. These two enzymes are found in many tissues in the body, including the liver and heart. If those tissues are damaged due to disease, the damaged cells release the enzymes into the bloodstream.

Removal of amino group from amino acid as ammonia is called deamination.

Two types:A) Oxidative deamination

B) Non Oxidative D.

OD:Site various tissue slice,liver and kidney.

D & l amino acid oxidases enzymes;

.Process of Oxidative Deamintion:

Take place in two steps:

1)Amino acid is first dehydrogenated by FP

2)Water molecule is added spontaneuosly.

Non-oxidative deamination:

.The amino groups of hydroxy amino acids as serine, therionine and hydroxy proline are enzymaticaly removed.

Occurs in liver and kidney.

This has low value in deamination mechanisms.

Transdeamination (Removal of α-amino group) by –a coupled process of transamination and deamination

o Transamination forms Glutamate in peripheral cells

o Deamination of glutamate forms ammonia in liver.

Urea is the major end product of nitrogen metabolism in humans and mammals. Ammonia, the product of oxidative deamination reactions, is toxic in even small amounts and must be removed from the body. The urea cycle or the ornithine cycle describes the conversion reactions of ammonia into urea. Since these reactions occur in the liver, the urea is then transported to the kidneys where it is excreted. The overall urea formation reaction is:

2 Ammonia + carbon dioxide + 3ATP ---> urea + water + 3 ADP

The first two reactions leading to the synthesis of urea occur in the mitochondria,

whereas the remaining cycle enzymes are located in the cytosol.

The urea cycle consists of five reactoions.

A) Increased urea levels in:• Excessive urea production- intake of high-protein diet 12 hours before blood sampling,- enhanced catabolism of body protein.• Incomplete urea clearance from the body- renal failure,- postrenal failure,- prerenal failure,-acquired hemolytic anemia (autoimmune)

-DM,LIVER CIROHSIS,NEPH SYNDROME.

B) Decreased urea levels in:• acromegaly,• acute and subacute necrosis of the liver,• after glucose infusion,• after hemodialysis,• celiac disease,• cystic fibrosis,• eclampsia,• hepatic failure.

Reference:

.BIOCHEMISTRY BY MN CHATTERJEA.

.ROSE AND WILSON ANATOMY & PHYSIOLGY.

.Wikipedia.