Nicotinamide adenine dinucleotide (NAD+) is a coenzyme found in all living cells. The compound is a dinucleotide, since it consists of two nucleotides joined through their phosphate groups, with one nucleotide containing an adenine base and the other containing nicotinamide. In metabolism, NAD+ is involved in redox reactions, carrying electrons from one reaction to another. The coenzyme is therefore found in two forms in cells: NAD+ is an oxidizing agent – it accepts electrons from other molecules and becomes reduced. However, it is also used in other cellular processes, notably as a substrate of enzymes that add or remove chemical groups from proteins, in posttranslational modifications. Due to the importance of these functions, the enzymes involved in NAD+ metabolism are targets for drug discovery. In organisms, NAD+ can be synthesized from basic building blocks (de novo) from the amino acids tryptophan or aspartic acid. Some NAD+ is also converted into nicotinamide adenine dinucleotide phosphate (NADP+); the chemistry of this related coenzyme is similar to that of NAD+, but it has different roles in metabolism.

Read the rest of this article: http://en.wikipedia.org/wiki/Nicotinamide_adenine_dinucleotide

_______________________________ Today's selected anniversaries:

1778:

An expedition led by James Cook reached Maui, the second largest of the Hawaiian Islands. http://en.wikipedia.org/wiki/Maui

1842:

The University of Notre Dame in South Bend, Indiana, USA, was founded as an all-male institution by members of the Roman Catholic Congregation of Holy Cross. http://en.wikipedia.org/wiki/University_of_Notre_Dame

1917:

Unable to resolve disputes with Eddie Livingstone, owner of the Toronto Blueshirts, the other ice hockey clubs of Canada's National Hockey Association officially agreed to leave that sports league and to form a new one: the National Hockey League. http://en.wikipedia.org/wiki/National_Hockey_League

1939:

The Soviet Red Army shelled Mainila, and then claimed that the fire originated from Finland across a nearby border, giving them a casus belli to launch the the Winter War a few days later.. http://en.wikipedia.org/wiki/Shelling_of_Mainila

1942:

World War II: Josip Broz Tito and the Yugoslav Partisans convened the first meeting of the Anti-Fascist Council of National Liberation of Yugoslavia at Bihać in northwestern Bosnia. http://en.wikipedia.org/wiki/AVNOJ

_____________________________ Wiktionary's word of the day:

limbate (adj): (biology, paleontology) Having a distinct edge; bordered http://en.wiktionary.org/wiki/limbate

___________________________ Wikiquote quote of the day:

Knowledge is proud that he has learned so much;

Wisdom is humble that he knows no more. --William Cowper http://en.wikiquote.org/wiki/William_Cowper