Tag: enzymes classification and cofactors

In enzymology, turnover number is the number of substrate molecules converted to products in a given unit of time on a single enzyme molecule when the enzyme is saturated with substrate. The enzyme catalase has highest turnover number value of 40,000,000 (per second per molecule of enzyme), followed by Carbonic anhydrase 400,000 (per second per molecule of enzyme), followed by acetylcholinesterase 140,000 (per second per molecule of enzyme), followed by $\beta$-lactamase 2000 (per second per molecule of enzyme).

The scientists listed in question had made some of the most outstanding contributions.
Pasteur discovered fermentation.  The biochemical process carried out by yeast which results in fermented products like beer and butter milk.
The first commercial standardized rennet was introduced by Chr Hansen in 1874. At that time, rudimentary methods were used to extract animal rennet from calves or adult bovine stomachs.
Diastase was the first enzyme discovered. It was extracted from malt solution in 1833 by Anselme Payen and Jean-Franois Persoz, chemists at a French sugar factory.
Waksman was awarded the Nobel Prize in Physiology or Medicine in recognition for his discovery of streptomycin, the first antibiotic active against tuberculosis.

The EC number 4.2.1.7 is assigned to the enzyme named altronate dehydratase or D-altronate hydro-lyase. This enzyme catalyses the dehydration of D-altronate and results in the formation of 2-dehydroxy-3-deoxy-D-gluconate and water. 

Phosphodiesterase is a hydrolase enzyme. So, it's EC number is 3.

Natural source of subtilin is bacteria Bacillus subtilis. Subtilisins are proteolytic enzymes mainly used in detergents and house hold cleaning products to remove proteinaceous deposits and stains.

Histone proteins are rich in basic amino acids and form the core around which the DNA is wound giving rise to nucleosome particles. DNA is wound around histones because basic amino acids are positively charged at physiological pH which facilitates winding of acidic or negatively charged DNA. Neutralization of positive charge, on basic amino acids of histone proteins, by chemical processes like reversible acetylation will lead to neutralization of attractive force between nucleosome core and DNA molecule. This will in turn lead to transcriptional activation (histone proteins are acetylated) and after transcription once again the histone proteins will be deacetylated restoring there positive charge, thus facilitating the tight binding between (negatively charged) DNA and (positively charged) histone core. Apart from reversible acetylation, histone proteins also undergo a number of other chemical modifications. Thus, acting as modulators for DNA metabolism.

in 1897, Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol, proving that fermentation was promoted by molecules that continued to function when removed from cells. Frederick W. Khne called these molecules as enzymes. The isolation and crystallization of urease by James Sumner, in 1926, provided a breakthrough in early enzyme studies. Sumner found that urease crystals consisted entirely of protein, and he postulated that all enzymes are proteins. In the absence of other examples, this idea remained controversial for some time. Only in the 1930s, was Sumners conclusion widely accepted, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found them also to be proteins.

Isoenzymes are an unique example in which the same reaction may be catalyzed by two or more different molecular forms of an enzyme. The multiple forms, called isozymes or isoenzymes, may occur in the same species, in the same tissue, or even in the same cell. The different forms of the enzyme generally differ in kinetic or regulatory properties, in the cofactor they use (NADH or NADPH for dehydrogenase isozymes, for example), or in their subcellular distribution (soluble or membrane-bound). Isozymes may have similar, but not identical, amino acid sequences, and in many cases they clearly share a common evolutionary origin. One of the first enzymes found to have isozymes was lactate dehydrogenase (LDH), which, in vertebrate tissues, exists as at least five different isozymes separable by electrophoresis. However, isoenzymes follow the same general mechanism of enzyme action, i.e., decreasing the activation energy of substrates for a reaction.