Allosteric Enzymes are Special Modulators. Why?

Allosteric Enzymes are Special Modulators. Why?

A Modulator is a metabolite which, when bound to the allosteric site of an enzyme, alter its kinetic characteristics. The modulators for allosteric enzymes may be either stimulatory or inhibitory. Many enzymes do not demonstrate hyperbolic saturation kinetics, or typical Michaelis-Menten kinetics. Graphs of initial velocity vs. substrate demonstrate sigmoidal dependency of v on S, much as we discussed with ... Read More »

Chemical Mechanisms of Enzyme Catalysis


How does an enzyme accomplish its tremendous enhancement of a reaction’s rate (as much as a billion-fold)? There is an upper limit to the activity of an enzyme: It cannot operate faster than the rate at which it encounters the substrate. In solution, this rate is approximately 108 to 109 times per second (sec-1). In the cell, enzymes acting on ... Read More »

Enzyme Kinetics : Kinetic Study of Enzymatic Reactions

Enzyme Kinetics : Kinetic Study of Enzymatic Reactions

Enzyme kinetics is the study of the chemical reactions that are catalysed by enzymes. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. Studying an enzyme’s kinetics in this way can reveal the catalytic mechanism of this enzyme, its role in metabolism, how its activity is controlled, and how ... Read More »

What is Mendelian Law and Mendelism?

Mendelism and mendel lawsMendelism and mendel laws

The contribution of Mendel to genetics is called Mendelism. Mendel is called the Father of Genetics. He was born in a peasant family in 1822 in Austria. In 1843, he entered the monastery at Brunn and in 1847 he was ordained as a Priest. After completing the theological studies, he worked as a substitute teacher in Mathematics and Greek. In ... Read More »

What is Enzyme Catalysis ?

What is Enzyme Catalysis ?

What is enzyme ? Enzymes are organic molecules, pretentious in nature that re specialized to catalyze biological reactions. Here these can be termed as “Biological Catalysts” (or) “Biocatalysts” (or) “Middle man of the Nature”. What is Enzyme ? What is the meaning? The name ‘enzyme‘ (enG=in; zymeG=Yeast) literal means “in yeast“. This was referred to denote one of the most ... Read More »

Biochemical Properties and Mechanism of ATP

biochemical mechanism and properties of ATP

ATP contains two phosphoanhydride bonds (connecting the 3 phosphates together) and one phosphoester bond (connecting a phosphate to the ribose ring). The pKa’s for the reactions H+ ATP3- —> ATP4- + H+ and HADP2- —> ADP3- + H+ are about 7.0, so the overall charges of ATP and ADP at physiological pH are -3.5 and -2.5, respectively. Each of the ... Read More »

The pH Concept: Basics and Importance in Biological System

pH concpet

The nature of the solution (acidic, alkaline (or) neutral) can be represented in terms of either hydrogen ion concentration (or) hydroxyl ion concentration. In 1909, Sorenson used a logarithmic scale for expressing the H+ concentration. This scale was called “pH”, Where “P” stands for ‘Power’ and ‘H’ for hydrogen ion concentration. Sorenson defines pH of a solution as “ The ... Read More »

Basics of Colligative Properties


Like pure solids, liquids and gases, solutions have well-defined physical properties (e.g., vapor pressure, boiling point, etc.). A change in a property of a solvent that depends on the concentration of dissolved solute(s) particles is called a colligative property. Colligative properties do not depend on the identity of either the solvent or the solute(s) particles (kind, size or charge) in ... Read More »

Coupled Reactions in Biological Systems

Coupling Reactions in Biological Systems

Every day your body carries out many non-spontaneous reactions. As discussed earlier, if a non-spontaneous reaction is coupled to a spontaneous reaction, as long as the sum of the free energies for the two reactions is negative, the coupling  reaction will occur spontaneously. How is this Coupled Reaction achieved in the biological system ? Living systems coupled reactions in several ... Read More »