Urease discovery

Until the discovery in 1975 of nickel in jack bean urease (which, 50 years previously, had been the first enzyme to be isolated in crystalline form and was thought to be metal-free) no biological role for nickel was known. Ureases occur in a wide variety of bacteria and plants, catalyzing the hydrolysis of urea,... 

John Northrop shared the Nobel Prize in chemistry in 1946 with Wendell Stanley, awarded to them for their preparation of enzymes and virus proteins in a pure form, and with James Sumner, for his discovery that enzymes can be crystallized. Although Sumner had been the first, in 1926, to crystallize an enzyme (urease) and to aver that enzymes were proteins, Northrop did more than any other scientist to establish that pure enzymes are indeed proteins. 

Buchners fermentation of sugar from yeast extracts Sumner s crystallization of urease Flemming s discovery of chromosomes Mendel s characterization of genes Miescher s isolation of nucleic acids Watson and Crick s stmcture of DNA... 

The hypothesis that nickel in animals may function as an enzyme cofactor has been stimulated by the discovery that urease from several plants and microorganisms is a nickel metalloenzyrne (20-25). Dixon al. (20) found that highly purified urease (E.C.3.5.1.5) from jack beans (Canavalia enslformls) contained stoichiometric amounts of nickel,... 

Nickel has been found essential for nutrition in pigs, also rats (Nielsen, 1975). The essential quantity is so much smaller than was required for the earlier-established essential metals, that searchers had to wait for the discovery of new analytical techniques, such as neutron activation. The enzyme urease (in beans) is nickel-dependent (Dixon et al, 1975). Several bacteria have reductases that need nickel, such as Methanobacterium and Desulphovibrio (Thauer, 1980), and so do bacterial carbon monoxide dehydrogenases (Deake, Hu and Ward, 1980). 

Since 1900, enzyme research has developed to such an extent that each single enzyme or a single property of a class of enzymes has proved sufficient to engage the attention of a group of investigators. Important dates are 1926, ciystallisation of urease (Sumner) 1932, discovery of flavin enzymes (Warburg) 1933, isolation of the co-enzymes 1935, isolation of virus protein (Stanley). 

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