Thiamin biochemistry

Absorption and Metabolism of Thiamin Biochemistry of Huamin Thiamin Deficiency Assessment of Thi in Status Determination of tite Thiamin Requiremoit Use of Thiamin in Maple Syrup Urine Disease Riboflavin... 

So what does riboflavin do As such riboflavin does nothing. Like thiamine, riboflavin must undergo metabolic change to become effective as a coenzyme. It fact, it undergoes two reactions. The first converts riboflavin to riboflavin-5-phosphate (commonly known as flavin adenine mononucleotide, FMN), about which we will say no more, and the second converts it to flavin adenine dinucleotide, FAD. The flavins are a class of redox agents of very general importance in biochemistry. FAD is the oxidized form and FADH2 is the reduced form. ... 

M. S. Hasson, A. Muscate, M. J. McLeish, L. S. Polovnikova, J. A. Gerlt, G. L. Kenyon, G. A. Petsko, D. Ringe, The crystal structure of benzoylformate decarboxylase at 1.6 A resolution, diversity of catalytic residues in thiamin diphosphate-dependent enzymes. Biochemistry 1998, 37, 9918-9930. 

Schellenberger A, Neef H, Golbig R, Hiibner G, Konig S (1990) Mechanistic aspects of thiamine pyrophosphate enzymes via site-directed substitutions of the coenzyme structure. In Bisswanger H, Ullrich H (eds) Biochemistry and physiology of thiamin diphosphate enzymes. VCH, Weinheim, p 3... 

When, in 1832, Wohler and Liebig first discovered the cyanide-catalyzed coupling of benzaldehyde that became known as the benzoin condensation , they laid the foundations for a wide field of growing organic chemistry [1]. In 1903, Lapworth proposed a mechanistical model with an intermediate carbanion formed in a hydrogen cyanide addition to the benzaldehyde substrate and subsequent deprotonation [2]. In the intermediate active aldehyde , the former carbonyl carbon atom exhibits an inverted, nucleophilic reactivity, which exemplifies the Umpo-lung concept of Seebach [3]. In 1943, Ukai et al. reported that thiazolium salts also surprisingly catalyze the benzoin condensation [4], an observation which attracted even more attention when Mizuhara et al. found, in 1954, that the thiazolium unit of the coenzyme thiamine (vitamin Bi) (1, Fig. 9.1) is essential for its activity in enzyme biocatalysis [5]. Subsequently, the biochemistry of thiamine-dependent enzymes has been extensively studied, and this has resulted in widespread applications of the enzymes as synthetic tools [6]. 

H. Bisswanger and J. Ullrich (Eds.), Biochemistry and Physiology of Thiamin Diphosphate Enzymes, VCH Publishers, Weinheim, 1991, pp. 1-453. 

Thiamin was the first of the vitamins to be demonstrated to have a clearly defined metabolic function as a coenzyme indeed, the studies of Peters group in the 1920s and 1930s laid the foundations not only of nutritional biochemistry but also of modern metabolic biochemistry and neurochemistry. Despite this, the mechanism by which thiamin deficiency results in central and peripheral nervous system lesions remains unclear in addition to its established coenzyme role, thiamin regulates the activity of a chloride transporter in nerve cells. 

Schellenberger A (1998) Sixty years of thiamin diphosphate biochemistry. Biochimica et Biophysica Acta 1385, 177-86. 

Alston TA and Abeles RH (1987) Enzymatic conversion of the antibiotic metronidazole to an analog of thiamine. Archives of Biochemistry and Biophysics 257,357-62. 

Bettendorff L (1996) A non-cofactor role of thiamine derivatives in excitable cells Archives of Physiology and Biochemistry 104, 745-51. 

Schenk G, Duggleby RG, and Nixon PF (1998) Properties and functions of the thiamin diphosphate dependent enzyme transketolase. International Journal of Biochemistry and Cell Biology 30,1297-1318. 

Lappert developed the thermolysis of an electron-rich olefin in the presence of a transition metal complex as another way to synthesise these compounds [4], When, in 1975, Clarke and Taube published their findings on carbon coordinated purine transition metal complexes [5], transition metal NHC complexes with functionalised NHC made their debut in biochemistry. The chemistry of carbenes from natural products became firmly established following the discovery that the catalytic activity of thiamine (vitamin Bl) is based on the intermediate formation of a carbene derived from thiazole [6-9] (see Figure 1.2). 

Miyoshi K, Egi Y, Shioda T, and Kawasaki T (1990) Evidence for in vivo synthesis of thiamin triphosphate by cytosolic adenylate kinase in chicken skeletal muscle. Journal of Biochemistry (Tokyo) 108, 267-70. 

Biochemistry of NAD NAD Used for Nonredox Purpose History of Niacin Nutrition Ass sment of Niacin Static Pharmacological Use of Nicotinic Add Thiamin... 

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