Biochemical aspects

Biochemical Aspects. The zinc-containing metalloenzyme carbonic anhydrase (carbonic hydro-lyase, EC 4.2.1,1) is specifically inhibited by univalent anions and by aromatic sulphonamides. AfT (25 for the binding reactions between bovine carbonic anhydrase and 3-methyl-2-acetylimino-l,3,4-thiadiazoline-5-sulphonamide (Methazolamide) is — 59.0kJmol and that for 5-phenyl-sulphonamido-l,3,4-thiadiazole-2-sulphonamide (CL 11366) is — 57.7kJmol The thermodynamic quantities did not correlate with the assumed structural features of the binding process.  

5-Substituted 2-anilino-l,3,4-thiadiazoles inhibit oxidative phosphorylation (in rat liver mitochondria) and photosynthetic phosphorylation (in spinach chloroplasts).  

Only a rough draft of the biochemistry of hydroporphyrins will be given here, pointing out some problems which have stimulated chemical investigations. 

Cytochromes and other proteins believed to contain iron chlorins were reviewed (85JA4207 85JA6069). 

The iron complex of sirohydrochlorin (119b) is the prosthetic group of nitrite (81 Mil) and sulfite reductases (75M17). These enzymes catalyze six-electron reductions yielding ammonia (sometimes NO, N20, and N2) and hydrogen sulfide, respectively. 

Heme dx isolated from Pseudomonas aeruqinosa and Paracocens denitrifi-cant was proposed not to be a chlorin but a 3,8-dioxoisobacteriochlorin similar to compound 55. This was confirmed by a comparison of the chromophore with that of a model compound (86JA1352). 

Structure 22 of the hydroporphyrin ligand system of factor F-430 has been elucidated mainly by a combination of incorporation and nC-NMR experiments (82HCA828 84HCA334). Isomerization of 22, which may occur during work-up was mentioned in Section III, D(85HCA1338). Factor F-430 (22) contains a chromophore system not previously encountered among natural products. 

Thiamine (Vitamin BO.— The structure and stability of the thiazolium ion are of particular interest because of its possible role as the active site in thiamine. In considering the function of sulphur in the mechanism of action of this vitamin, Breslow was led to discuss the structure of thiazolium ylides he suggested an overlap of a sulphur d y orbital with the filled spxPy orbital at C-2. d-a Overlap as a possible stabilizing factor in thiazolium ylides, suggested by Olofson and his co-workers, has found support from quantitative comparisons of oxazolium and thiazolium ions. Thus, the relative second-order rate-constant for the exchange of 

Wada and G. Nakagawa, Nippon Kagaku Zasshi, 1968, 89, 951 Chem. Abs., 1969, 70, 16 854n). 

Breslow, in The Mechanism of Action of Water-soluble Vitamins , Ciba Study Group No. 11, Little, Brown and Co., Boston, p. 65 Ann. New York Acad. Sci., 1962, 98, 445. 

H-2 in 3,4-dimethyl-oxazolium, -thiazolium (133), and 1,3,4-trimethyl-imidazolium ion are resi cctively 10 10 1. On the other hand, the i C-H coupling constants at the 2-position in homologous imidazolium and thiazolium ions do not differ appreciably from one another, indicating 

Thiamine pyrophosphate is the essential coenzyme in the enzymatic decarboxylation of pyruvate to acetaldehyde. It has been proposed that the decarboxylation proceeds by way of 2-(l-carboxy-l-hydroxyethyl)-thiamine pyrophosphate [(134a) arising from pyruvic acid and thecoenzyme]. 

---

There has been a surge of research activity in the physical chemistry of membranes, bilayers, and vesicles. In addition to the fundamental interest in cell membranes and phospholipid bilayers, there is tremendous motivation for the design of supported membrane biosensors for medical and pharmaceutical applications (see the recent review by Sackmann [64]). This subject, in particular its biochemical aspects, is too vast for full development here we will only briefly discuss some of the more physical aspects of these systems. The reader is referred to the general references and some additional reviews [65-69]. 

R. Filler and Y. Kobayashi, Biochemical Aspects of Fluorine Chemist, Kodansha Scientific Books, Tokyo, and Elsevier Biomedical Press, Amsterdam, 1982. M. Hudlicky, Chemistry of Organic Fluorine Compounds, 2nd ed., Ellis Horwood, Ltd., Chicliestet, UK, 1976. 

Fluormated Carbohydrates Chemical and Biochemical Aspects Taylor, N F, Ed, ACS Symposium Senes 374, Amencan Chemical Society Washington, DC, 1988... 

For this reason dual terminology is in use for the aza analogs. The first, derived from the principal pyrimidine and purine derivatives by means of the prefix aza- is used almost exclusively in biochemical papers in organic chemistry is it used together with the systematic names) wherever it is desired to compare the properties of the natural bases and of their aza analogs. The systematic terminology is naturally used in the older literature where no biochemical aspects of the compounds were considered, and in some newer work of strictly chemical nature. Since the numbering of the substituents is in some cases different for the different systems, we shall discuss this in more detail later. ... 

The chemistry of the 6-aza analogs of pyrimidine bases which has been developed from the biochemical aspect since about 1956 was based on work reported in relatively numerous older papers. In spite of the fact that 6-azauracil was prepared only in 1947 and suitable syntheses were described only quite recently, substances of this type and methods of their preparation had been known for a long time. The chemistry of 6-aza analogs of pyrimidine bases is therefore relatively closely linked with the chemistry of the 1,2,4-triazine derivatives. 

Here we will focus on the biochemical aspects. The techniques of isolating enzymes, the process of enzyme immobilisation and the behaviour of immobilised enzyme reactors are discussed in detail in the BIOTOL text Technological Applications of Biocatalysts", so will not deal with these aspects in detail here. In outline, however, once the desired enzyme is isolated, it is attached to a carrier material. In order to ascertain sufficient accessibility of the enzyme, a bifunctional spacer molecule is attached to the carrier ... 

In Mollusca, bioluminescence occurs in a great variety of organisms having distinctly different appearances, such as the classes Gastropoda (limpets, snails and sea hares), Bivalvia (clams), and Cephalopoda (squids and octopuses). All luminous molluscs currently known are marine organisms, except the New Zealand fresh water limpet Latia neritoides and the Malaysian land snail Quantula (Dyakia) striata. No information is yet available on the biochemical aspects of the Quantula luminescence. 

Viviani, V. R., and Bechara, E. J. H. (1993). Biophysical and biochemical aspects of phengodid (railroad worm) bioluminescence. Photochem. Photobiol. 58 615-622. 

Iron (Other Biochemical Aspects) (see also Tables 17 and 18)... 

Biochemical aspects of molybdenum coordination chemistry. J. T. Spence, Coord. Chem. Rev., 1969, 4, 475-498 (74). 

Biochemical aspects of Fe—S linkages in non-aqueous heme iron proteins with special reference to Andrenodoxin. T. Kimura, Struct. Bonding (Berlin), 1968, 5, 2-40 (72). 

The versatile chemistry of 1,4-diazines organic, inorganic and biochemical aspects. W. Kaim, Angew. Chem., Int. Ed. Engl., 1983, 22,171-190 (217). 

S. Oae, T. Okuyama (Eds.), Organic Sulfur Chemistry Biochemical Aspects,... 

Some Biochemical Aspects of Carbon Isotopic Paleodiet Studies... 

BIOCHEMICAL ASPECTS OF CARBON ISOTOPIC PALEODIET STUDIES... 

Schwarcz, H.P. (2000). Some biochemical aspects of carbon isotopic paleodiet studies. In Biogeochemical Approaches to Paleodietary Analysis (S.H. Ambrose, M.A. Katzenberg, Eds.), Kluwer Academic/Plenum Publishers New York, pp. 189-209. (http //dx.doi.org/10.1007/0-306-47194-9 10)... 

Agosta, W. (1996). Bombardier Beetles and Fever Trees—A highly readable account of chemical warfare, without much detail on chemical or biochemical aspects. 

Clark, R.B. (1992). Marine Pollution, 3rd edition, Clarendon Press, Oxford—Offers a readable account of marine pollution caused by crude oil, but does not deal with biochemical aspects. 

Lardy H, Shrago E Biochemical aspects of obesity. Annu Rev Biochem 1990 59 689. 

Randle PJ The glucose-fatty acid cycle—biochemical aspects. Atherosclerosis Rev 1991 22 183-... 

Cutler, D. F., Brandham, P. E., Carter, S. and Harris, S. J. 1980. Morphological, anatomical, cytological and biochemical aspects of evolution in East African shrubby species of Aloe L. (Liliaceae). Bot. J. Linn. Soc. 80 293-317. 

RUKMINI c, RAGHURAM T c (1991) Nutritional and biochemical aspects of the hypolipidemic action of rice bran oil. JAm Coll Nutr, 10 593-601. 

Beyer, R, Croncke, U., and Nievelstein, V., Biochemical aspects of carotene desaturation and cyclization in chromoplasts membranes from Narcissus pseudonarcissus. Pure Appl. Chem. 66, 1047, 1994. 

Molecular genetic and biochemical aspects of pectin degradation in Aspergillus... 

Reviews on the microbial metabolism of hydrocarbons with biochemical aspects are available, and inclnde those of Britton (1984) on alkanes, and of Morgan and Watkinson (1994) that also includes cycloalkanes and some aromatic compounds. Virtually all the issues that are discussed in these recur in the examples that are used as illustration. Some broad generalizations are summarized ... 

Kimura, T. Biochemical Aspects of Iron Sulfur Linkage in None-Heme Iron Protein, with Special Reference to Adrenodoxin . Vol. 5, pp. 1-40. 

Yasutake A, Nakano A, Miyamoto K, Eto K. 1997. Chronic effects of methylmercury in rats. I. Biochemical aspects. Tohoku J Exp Med 182 185-196. 

Goldman, R., Goldstein, L. and Katchalski, C.I. (1971) in Biochemical Aspects of Reactions on Solid Supports, Ed. G.P. Stark, Academic Press. 

---