Protein anino acid and alcohol

Proteins and Amino Acids

ByZahid gul

University of peshawar

Protein

• Proteins are the most abundant and functionally

diverse molecules in living systems where they constitute 50% or more of their dry mass.

• The word protein is derived from the Greek Protos, which means the first or supreme.

• Proteins are nitrogenous macromolecules,composed

of aminoacids linked by peptide bond.

Amino acid

•monomers of protein.•consists of carbon,hydrogen,oxygen,nitrogen

and some contain sulfur.• our body protein are made up from 20 types

amino acids.

• Although more than 300 naturally occurring amino acids are known but only 20 amino acids take part in the formation of all types of proteins,plants as well as animal in origin.

• These 20 amino acids are known as Primary,Standard or normal amino acids.

Biochemistry For Medics 5

General structure of an amino acid

Each amino acid (except proline) has a carboxyl group, an amino group and a distinctive side chain bonded to the alpha carbon atom. At physiological pH the carboxyl group is dissociated forming the negatively charged carboxylate ion(-COO-), and the amino group is protonated(-NH3

+)

7/5/2012

• Semi-essential aminoacids.

Two amino acid cysteine and tyrosine can be sythesiszed from essential amino acid{thionine and phenyalanine} and can also be consumed in diet.

• the process of amino acid formation from other amino acid is called transamination

Classification of proteins regarding nutrition

• HIGH QUALITY PROTEINS

Protein that contain all the nine essential amino acid

• LOW QUALITY PROTEINS

Protein that lack one or more essential amino acid

Protein for Our Body

Protein synthesis

• DNA contains coded instructions for protein synthesis in the form of three nucleotide per unit of instruction called codon, each codon represent a specific amino acid.

• Protein synthesis consists of two main steps,• Transcription and translation.

Transcription

• Formation of mRNA from DNA is called transcription.

• Transcription occurs in three stages: 1.Initiation: – RNA polymerase binds to DNA at a specific

sequence of nucleotides called the promoter. – The promoter contains an initiation site where

transcription of the gene begins.

Transcription

– RNA polymerase than unwinds DNA at the beginning of the gene.

• 2.Elongation: – Only one of the unmound DNA strands acts as a

template for the RNA synthesis. – RNA polymerase can only add nucleotides to the

3' end of the strand. – Free nucleotides from the cytoplasm are paired

up with their complementary base on the exposed DNA template.

Transcription

Termination: RNA polymerase continues to elongate until it

reaches the terminator, a specific sequence of n Transcription stops and mRNA polymerase and the new mRNA transcript are released from DNA.

The DNA double helix reforms. • And the mRNA enters into the cytoplasm.

translation

• Translation may be divided into three distinct steps.

translation

• Inatiation,results in the formation of an initiation complex in which the ribosome is bound to the specific initiation (start) site on the mRNA while the initiator tRNA is annealed to the initiator codon and bound to the ribosome.

• , elongation consists of joining amino acids to the growing polypeptide chain according to the sequence specified by the message. Incorporation of each amino acid occurs by the same mechanism. Thus, the same steps are repeated over and over again until the termination codon is reached in the message. The termination codon gives the signal for the third and last stage of protein synthesis, the termination in which the ready-made protein is released from the ribosome.

Structural

Movement

Transport

Storage

Hormone

Protection

Enzymes

Collagen; bones, tendons, cartilageKeratin; hair, skin, wool, nails, feathers

Myosin & Actin; muscle contractions

Hemoglobin; transports O2Lipoproteins; transports lipids

Casein; in milk. Albumin; in eggs

Insulin; regulates blood glucoseGrowth hormone; regulates growth

Immunoglobulins; stimulate immunity Sucrase; Pepsin;

Functions of Proteins

Protein Deficiency

• Protein-energy malnutrition (PEM)World’s most widespread malnutrition problemIncludes both marasmus and kwashiorkor and states

of overlap

MARASMUS. { to waste away}

symptoms.Muscle wasting, Impaired immunity ,Lethargy,

Vomiting, Delayed wound healing, Loss of fat stores and muscles

Causes.•due to diet containing less amount of protein and

energy.•no breast feeding or stop breast feeding in early

month•working mother feed their infants through bottle

which also can cause this condition.• in hospitalized patient marasmus can be caused by

lack of proper diet.

Kwashiorkor

• symptoms :• change in skin and hair color (reddish-orange color)• fatigue• diarrhea• loss of muscle mass• failure to grow or gain weight• damaged immune system, which can lead to more frequent and

severe infections• irritability• rash• large belly that sticks out

Causes

• Kwashiorkor is a world from ghana that means “ the disease that the first child gets when the new child comes”

• When the breast feeding is no longer possible for the first child the child diet changes and can not fulfill the energy and protein requirement of he child,

• The child also has infections and parasites,

Protein Digestionand

absorbtion

Protein Digestion

• is the degradation of proteins by cellular enzymes enzymes in a process called hydrolysis.

• Protein digestion takes place in two different phases:– In the stomach– In the small intestine

• Both of these phases of digestion are based on several types of enzymes that are called proteinases and proteases.

In the Stomach : start of protein Digestion

Gastrin-stimulates Parietal cells to secrete HCL; Chief cells of the gastric glands to secrete pepsinogen

Hydrochloric acid-Denatures protein structure-Activates pepsinogen (zymogen) to pepsin

Pepsin -hydrolyzes proteins to smaller polypeptides and some free amino acids.

In the intestine

. The remainder of protein digestion occurs in the small intestine as the result of the action of enzymes

such as trypsin (secreted by the pancreas) and peptidases (located in the cells that line the small intestine).

In the Small Intestine : enzymes

Secretin- stimulates the pancreas to secrete bicarbonate into the small intestine to neutralize the gastric HCl

Cholecystokinin-stimulates secretion of several pancreatic enzyme with activity optima pH 7 to 8.

In the Small Intestine

Trypsin- activates chymotrypsinogen chymotrypsin

procarboxypeptidasescarboxypeptidasesproelastaseelastase

-further hydrolyze the peptides that were produced by pepsin in the stomach specifically the peptide bonds next to lysine and arginine

Chymotrypsin-cleaves peptide bonds

Carboxypeptidase A & B-cleave amino acids from the acid (carboxyl) ends of polypeptides

Elastase and collagenase-cleave polypeptides into smaller polypeptides and tripeptides

Intestinal tripeptidases-Cleave tripeptides to dipeptides and amino acids

Intestinal dipeptidases-cleave dipeptides to amino acids

Intestinal aminopeptidases -cleave amino acids from the amino ends of small polypeptides (oligopeptides)

Amino acids absorbed

Free amino acid small intestine(villi)Liverblood circulation

Metabolism of -amino acids

Alcohol

• Alcohol are chemically called ethanol.• Alcohol are classed as depressant because it

slows down vital function resulting in slurred speech, unsteady movement, disturbed perception and inability to react quickly,

• Alcohol overdose can causes coma and death also.

• Besides these and many other effects alcohol is a good source of energy

Alcohol metabolism

• Metabolism of alcohol is dependent on many factors like gender, race, size and physical condition.

• Alcohol is metabolized by three pathways.• Alcohol dehydrogenase pathway.• Microsomal ethanol oxidizing system.• Catalase pathway.

Alcohol dehydrogenase pathway

Ethanol NAD+ NADH+H Acetaldehyde NAD+ NADH+H acetyl-CoA

Microsomal ethanol oxidizing pathway

• Excessive amount of ethanol is metabolized by the liver through MEOS.

• Liver uses the MEOS to metabolized drugs and other foreign substances.

• In MEOS NADPH+H are used in the first step,• Whereas NADH+H are produced during

alcohol dehydrogenase pathway.

Microsomal ethanol oxidizing pathway

Ethanol o2 NADPH+H NADP

Acetaldehyde

acetyl-coA

Catalase pathway

• Minor path for metabolizing alcohol,• It is located in the peroxisomes,

Ethanol H2O2 H2O

Acetaldehyde

Health problem and alcohol

• Alcohol is the third leading cause of preventable death in north America

• Causes of alcohol are heart failure, cancer, liver cirrhosis, motor vehicle accidents, hypertension, hemorrhagic stroke, osteoporosis, brain damage, suppression of immune system.

• Liver cirrhosis affects about 2 million people in USA, AND IS the second leading cause of the liver transplants.

Health problem and alcohol

• In 2011 about 35,000 American died of liver cirrhosis.

• Increase heart muscle damage, blood clotting and blood pressure.

• Reduce insulin sensitivity and damage to pancreas,

• Damage skeletal muscle,