| Share
 

guanine

guanine (gwäˈnēn) [key], organic base of the purine family. It was reported (1846) to be in the guano of birds; later (1879–84) it was established as one of the major constituents of nucleic acids. The accepted structure of the guanine molecule was proposed in 1875, and the compound was first synthesized in 1900. When combined with the sugar ribose in a glycosidic linkage, guanine forms a derivative called guanosine (a nucleoside), which in turn can be phosphorylated with from one to three phosphoric acid groups, yielding the three nucleotides GMP (guanosine monophosphate), GDP (guanosine diphosphate), and GTP (guanosine triphosphate). Analogous nucleosides and nucleotides are formed from guanine and deoxyribose. The nucleotide derivatives of guanine perform important functions in cellular metabolism. GTP acts as a coenzyme in carbohydrate metabolism and in the biosynthesis of proteins; it can readily donate one of its phosphate groups to adenosine diphosphate (ADP) to form adenosine triphosphate (ATP), an extremely important intermediate in the transfer of chemical energy in living systems. GTP is the source of the guanosine found in RNA and deoxyguanosine triphosphate (dGTP) is the source of the deoxyguanosine in DNA, and thus guanine is intimately involved in the preservation and transfer of genetic information. Guanine is said to account for the iridescence of fish scales and the white, shiny appearance of the skin of many amphibians and reptiles.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on guanine from Infoplease:

See more Encyclopedia articles on: Biochemistry


Premium Partner Content
HighBeam Research
Documents Images and Maps Reference
(from Newspapers, Magazines, Journals, Newswires, Transcripts and Books)

Research our extensive archive of more than 80 million articles from 6,500 publications.

Additional search results provided by HighBeam Research, LLC. © Copyright 2005. All rights reserved.

24 X 7

Private Tutor

Click Here for Details
24 x 7 Tutor Availability
Unlimited Online Tutoring
1-on-1 Tutoring