The German-born British biochemist Hans Krebs received the 1953 Nobel Prize in Physiology or Medicine for his identification of the cycle in 1937. Its central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism and may have originated abiogenically. In addition, the cycle provides precursors of certain amino acids, as well as NADH, a reducing agent, which are used in numerous other reactions.
The citric acid cycle, also known as the TCA cycle (tricarboxylic acid cycle) or the Krebs cycle, is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The peace was sealed by the marriage of Zufar's daughter Rabab to the caliph's son Maslama. Zufar's troops were pardoned, rewarded and integrated into the Umayyad military. After three sieges of Qarqisiya from 685 to 691, Zufar negotiated a peace with Caliph Abd al-Malik. Zufar then set up headquarters in Qarqisiya and led the Qays tribes against the Kalb. At the Battle of Marj Rahit in 684, the Qays were crushed by the Umayyads and their allies. After Yazid died, Zufar supported Abd Allah ibn al-Zubayr's bid against the Umayyads. During the Second Muslim Civil War he served Caliph Yazid I against anti-Umayyad rebels in the Battle of al-Harra in 683. In 657 he fought under Mu'awiya against Ali at the Battle of Siffin. During the First Muslim Civil War he led his tribe in A'isha's army against Caliph Ali at the Battle of the Camel in 656. 695) was a Muslim commander from the Arab tribe of Banu Amir, and the leader of the Qays faction in the late 7th century. Map of the political situation in the caliphate, c.