Proteins {enzyme}| can be catalysts. Enzyme and ribozyme catalysts regulate biochemical reactions. Coenzymes can bind to or assist enzymes.
history
Schwann discovered pepsin [1825], which cuts proteins. Robiquet and Boutron discovered emulsin [1830]. Leuchs discovered ptyalin [1831]. Payen and Persoz discovered amylase [1833], which cuts starches. Corvisart discovered trypsin [1856], which cuts proteins. Kuhne invented the word enzyme [1878]. Bertrand discovered need for coenzymes [1897]. Arthur Harden and William John Young discovered coenzyme for zymase [1906]. Henri studied enzyme kinetics and proposed enzyme-substrate complex [1903]. Barger and Stedman discovered that physostigmine inhibited cholinesterase [1923], which metabolizes choline. Jones and Perkins discovered ribonuclease [1923], which cuts RNA. Enzymes are proteins [1925]. Briggs and Haldane used steady state for enzyme kinetics [1925]. Sumner discovered urease [1926], which metabolizes urea. Stedman discovered acetylcholinesterase [1932], which metabolizes acetylcholine. Aeschlimann discovered that neostigmine inhibited cholinesterase [1931]. Hellerman hypothesized need for thiol groups in enzymes, as did Bersin and Logemann [1933]. Hellerman hypothesized need for metal bridges in enzymes [1937]. Mann and Keilin discovered that sulfanilamide inhibited carbonic anhydrase [1940]. Sanger and Tuppy found insulin amino-acid sequence [1951]. Sutherland discovered cyclic AMP in animal cells [1956]. Koshland hypothesized enzyme conformation changes upon binding [1958]. Kendrew used x-ray crystallography on myoglobin [1958]. Merrifield developed solid-phase peptide synthesis and built insulin and ribonuclease [1963].
types
Chymotrypsin, cytochrome, diastase, flavin, lipase, lysozyme, nuclease, RNA polymerase, thermolysin, and DNA polymerase are enzymes.
transition states
About 100,000,000 transition-state shapes exist for enzymes.
In competitive inhibition, inhibitor shape can be similar to substrate shape, so inhibitor can bind to enzyme at substrate site {active site}.
In non-competitive inhibition, inhibitors can bind to enzymes at other sites {allosteric site} to alter active sites.
Molecules {coenzyme}| can bind to enzymes to activate them. Michaelis and Wollman discovered that free radicals formed from alpha-tocopherol [1950]. Lipmann isolated coenzyme A [1945]. Mitchell, Snell, and Williams isolated folic acid [1941]. O'Kane and Gunsalus isolated lipoic acid [1948]. Metals can be coenzymes [1930]. Jansen and Donath isolated thiamine [1926]. Fildes hypothesized that molecules similar to natural substrates or coenzymes compete and are therapeutic. Methotrexate treats leukemia (Farber) [1946].
Post-transcription, enzymes {proteolytic enzyme} can cleave terminal amino acids and break peptide chains into pieces: proteinase, peptidase, pepsin, trypsin, chymotrypsin, carboxypeptidase, amino peptidase, dipeptidase, endopeptidase, and exopeptidase.
Reagents {substrate} can bind to enzymes at active sites.
Enzyme precursors {zymogen} can split or react to create enzymes.
Molecules {inhibitor} can bind to enzyme to reduce reaction rate {enzyme inhibition}.
Inhibitor shape can be similar to substrate shape, so inhibitor can bind to enzyme at active site {competitive inhibition}.
Inhibitor can bind to enzyme at allosteric site to alter active site {non-competitive inhibition}.
Inhibitor can bind directly to enzyme-substrate complex to change activation energy {uncompetitive inhibition}.
5-Chemistry-Biochemistry-Protein-Kinds
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Date Modified: 2022.0225