FSc Notes Part 2 Chemistry Important Chemicals Plaster Of Paris, Enzymes and Amino Acid

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Plaster Of Paris

Definition

The hemi hydrate form of calcium sulphate is known as Plaster of Paris.

Molecular Formula

The molecular formula of Plaster of Paris is

CaSO4. 1/2 H2O

Preparation of Plaster of Paris

When Gypsum (CaSO4.2H2O) is heated to about 100ºC, it loses some water of crystallization and is converted to Plaster of Paris.

Uses of Plaster of Paris

1. At high temperatures gypsum loses all the water of crystallization to give anhydrous calsium sulphate.
2. 2. It is used in manufacture of H2SO4.
3. 3. It is used in making of cement.
4. 4. It is used in the preparation of moulds used in surgery and castings.

Enzymes

Definition

Enzymes are a class of proteins which catalyze all types of bio-chemical reaction, such as digestion, respiration, muscular contraction and metabolism.

In all living structures, the biological reactions are catalyzed by Enzymes, even the biosynthesis of enzymes by living things is also catalyzed by enzymes.

Composition of Enzymes

The composition of enzymes is based on two main components, namely

1. Proteinic Component
2. Non Proteinic Component

1. Proteinic Component

Enzymes are Protein in nature and the proteinic component of enzymes is called Apoenzyme.

2. Non Proteinic Component

Most of the enzymes need a non proteinic component for their activity, which is known as Cofactor. Without Cofactor enzymes cannot show any enzymatic activity. In some enzymes the Cofactor is simply metal ion or organic molecules or ions.

Functions of Enzymes

Enzymes accelerate the rate of reaction as well as drive a reaction to completion, which normally does not occur at room temperature. At the end these are regenerated unchanged. They provide a reaction path way with a lower energy of activation.

Classification of Enzymes

Enzymes are classified into six major classes on the basis of type of reaction it catalyze.

1. Oxido Reductases – Redox Reaction
2. Transferases – Transfer of Group
3. Hydrolases – Hydrolysis Reaction
4. Lyases – Addition Reaction
5. Isomerases – Conversion of Isomers
6. Ligases – Condensation Reaction

Factors Effecting Enzyme Activity

Following are the factors which effect enzyme activity.

1. pH

Every enzyme has its own optimum pH at which it shows maximum activity.

2. Temperature

Every enzyme has its own optimum temperature at which its shows maximum activity. Most of the enzymes show maximum activity between 37ºC – 50ºC.

3. Other Factors

Other factors which effect the enzyme activity are substrate concentration, enzyme concentration and presence of certain ion etc.

Amino Acid

Definition

Amino Acids are the common compounds which contain both carboxylic and amino group.

Carboxylic group is acidic whereas, the amino group is basic.

General Formula

The general formula of amino acid is

R-CNH2H-COOH

Where,

R = alkyl Group

NH2 = Amino Group

COOH = Carboxylic Group

These amino acids are also called α – amino acids because the amino groups is present on α – carbon atom to the carboxylic group.

Classification of Amino Acids

On the basis of number of carboxylic group (-COOH) and amino group (-NH2). Amino acids are classified into the following three classes.

1. Neutral Amino Acids
2. Acidic Amino Acids
3. Basic Amino Acids

1. Neutral Amino Acids

Those amino acids, which have equal number of -COOH and -NH2 groups, are called Neutral Amino Acids.

Example

1. Glycine (CH2NH2COOH)
2. Alanine (CH3-CH-NH2-COOH)

2. Acidic Amino Acids

Those amino acids, which have greater number of -COOH than -NH2 groups are called Acidic Amino Acids.

Example

1. Asparite [CH2NH2CH(COOH)2]
2. Glutamic [HOOC-CH2-CH2-CH-NH2-COOH]
3. Basic Amino Acids

Those amino acids, which contain greater number of -NH3 than -COOH groups, are called Basic Amino Acids.

Example

1. Lysine [H2N-(CH2)4-CH-NH2-COOH]

Zwitter Ion

When the hydrogen ion of carboxylic group is accepted by amino group in amino acid then Zwitter ion is formed.

Zwitter ion is a German word, its meaning is two charged ion, i.e. both positive and negative charge. This ion is electrically neutral. In solution amino acid, exist in following ionic form.

Peptide Bond Or Peptide Linkage

In the polymers of amino acids, different amino acids are linked together through a bond or linkage, which is known as peptide bond or Peptide bond or Peptide Linkage.

When the hydrogen of amino acid combine with the OH group of other amino acid to form water, the bond between Nitrogen of one amino acid and carbon of other amino acid is formed which is known as Peptide Bond or Linkage. This peptide bond is formed in proteins which are the polymers of amino acids.

Essential Amino Acids

Naturally occurring amino acids are known as, essential amino acids.

A large number of synthetic amino acids are known, but only 20 amino acids occur in nature.

Properties of Amino Acids

The properties of amino acids are as follows.

1. Amino acids are soluble in water, but insoluble in organic solvents.
2. Amino acids are solids.
3. Amino acids have high melting point.
4. They donate or accept proton in the medium in which they are dissolved.

Function of Amino Acids

The role of amino acids in the human body is as follows.

1. Amino Acids can be synthesized back into Proteins.
2. Amino Acids oxidize to provide energy.
3. Amino Acids may be transformed into carbon hydrates or fats.