BIOCHEMISTRY : MODULE 4

Proteins

Are biomolecules that contain many amide bonds, formed by joining amino acids.

Amide bonds

Bonds that join amino acids to form protein.

Peptide Bonds

Amide bonds are also known as?

Amino Acids

Building blocks of protein?

Amide Bonds

C-N

50%

Protein account for ___ of the dry weight of the human body.

15%

Protein account for ___ of the overall weight of the human body.

No

Can you store proteins?

Yes

Should we consume protein daily?

it cannot be stored

Why should we consume protein daily?

0.8 grams

Recommended daily intake of proteins for adults?

Meat and Milk

Dietary protein comes from eating ____ and ____.

• Amino Group (NH₂)

• Carboxyl Group (COOH)

What functional groups does an amino acid contains?

Glycine

Simplest amino acid?

R group (side chain)

What determines the identity of the amino acid?

N atom

The Basic amino acid

COOH group

Acidic amino acid

NH₂

Amino acid’s Base?

COOH

Amino acid’s acid?

Zwitterion

A proton transfers from the acid to the base froms a

neutral

the basic and the acidic part of the amino acids causes it to be ____.

• Ala

• Asn

• Cys

• Gln

• Gly

• Ile

• Leu

• Met

• Phe

• Pro

• Ser

• Thr

• Val

• Trp

• Tyr

Neutral Common Amino Acids?

• Asp

• Glu

The acidic amino acids

• Arg

• His

• Lys

The Basic Amino Acids

Chirality Center

all amino acids have a _____ on the a carbon.

Left

L amino acids have the -NH₃⁺ group on the ___.

Right

D amino acids have the -NH₃⁺ group on the ___.

• A

• G

• I

• L

• V

(GILVA)

Alipathic non-polar side chains?

• F

• Y

• W

Aromatic Side Chains

• S

• T

Hydroxyl-containing side chains

• C

• M

Sulfur containing side chains

• D

• E

Acidic Amino acids

• N

• Q

Amidic Side Chains

• H

• K

• R

Basic Amino Acids

• P

Imino Acid

• A

• I

• L

• M

• F

• P

• W

• Y

• V

• G

Non-Polar Amino Acids

• N

• C

• Q

• S

• T

Polar Amino Acids

• D

• E

Acidic Amino Acids

• R

• H

• K

Basic Amino Acids

Essential Amino Acids

are essential to the normal functioning of the human body.

Essential Amino Acids

Since the body is not capable of synthesizing them, they must be supplied in

our diets.

• F

• V

• W

• T

• I

• M

• L

• K

• H

• R

Essential Amino Acids for Humans

Complete Proteins

• Supplies all the essential amino acids

• usually from animal sources

Incomplete Proteins

• Is deficient in one or more essential amino acids

• usually from plant sources

Proteoses

Hydrolysis of Protein : Protein → _______

Peptones

Hydrolysis of Protein : Proteoses → ________

Polypeptides

Hydrolysis of Protein : Peptones → _______

Tripeptides

Hydrolysis of Protein : Polypeptides → ______

Dipeptides

Hydrolysis of Protein : Tripeptides → ______

Amino Acids

Hydrolysis of Protein : Dipeptides → _______

Complete Dietary Proteins

a protein that contains all of the essential amino acids in the same relative amounts in which the body needs them.

Incomplete Dietary Protein

is a protein that does not contain adequate amounts, relative to the body’s needs, of one or more of the essential amino acids.

Limiting Amino Acid

is an essential amino acid that is missing, or present in inadequate amounts, in an incomplete dietary protein.

Protein

_____ from animal sources is usually a complete dietary protein.

Casein

______ from milk and proteins found in meat, fish, and eggs are complete dietary proteins.

gelatin

____ a protein in which tryptophan is the limiting amino acid.

plant sources

Protein from _______ tends to be incomplete dietary protein.

Soy

_____ is the only common plant protein that is a complete dietary protein.

Complementary dietary proteins

are two or more incomplete dietary proteins that, when combined, provide an adequate amount of all essential amino acids relative to the body’s needs.

Genetic modification techniques

_________ can improve a plant’s protein by causing it to produce increased amounts of amino acids that it normally has in short supply.

Amphoterism

Amino Acids that can react to either as an acid or a base.

Isoelectric pH

pI means?

Amino Acids

pI is only applicable for?

zwitterion ; isolectric pH

An amino acids exists as a neutrally charges ______ at a certain pH, the ________.

Isoelectric Point

pH at which there is no migration toward either electrode is called the _____.

Neutral

Isoelectric point is electrically ____.

pI - Isolectric pH

Is the neutral pH of amino acids.

6.00

pI of Alanine

10.76

pI of Arginine

5.41

pI of Asn

2.77

pI of Asp

5.07

pI of Cys

3.22

pI of Glu

5.65

pI of Gln

5.97

pI of Gly

7.59

pI of His

6.02

pI of Ile

5.98

pI of Leu

9.74

pI of Lys

5.74

pI of Met

5.48

pI of Phe

6.30

pI of Pro

5.58

pI of Ser

5.60

pI of Thr

5.89

pI of Trp

5.66

pI of Tyr

5.96

pI of Val

Gains a proton

pH < isoelectric = carboxylate anions?

Positive

pH < isoelectric = Amino acids net charge?

Loses a proton

pH > isoelectric = Ammonium cation?

Negative

pH > isoelectric = amino acid net charge?

pH > isoelectric =

Adding Base

pH < isoelectric =

Adding Acids

Peptides and Proteins

Are formed when amino acids are joined together by amide bonds.

Dipeptide

Two amino acids joined together by one amide bond.

Peptide Bond

Amide bond is also called a ____.

Tripeptide

_____ has 3 amino acids joined together by 2 amide bond.

40

Proteins have __ amino acids.

Alanyl Serine

Combine amino acids Ala and Ser.