Prosthetic groups simple

Molecular weight. The molecular weight of C. hilgendorfii luciferase reported in the past varies considerably across a range of 50,000-80,000 (Chase and Langridge, 1960 Shimomura etal., 1961, 1969 Tsuji and Sowinski, 1961 Tsuji et al., 1974) it appears most likely to be 60,000-70,000. The luciferase is an acidic protein with an isoelectric point of 4.35 (Shimomura et al., 1961). The absorption spectrum of luciferase is that of a simple protein without any prosthetic group, showing a peak at 280 nm. Absorbance value at 280 nm of a 0.1% luciferase solution is approximately 0.96 (Shimomura etal., 1969). 

This behavior, as well as complementary observations, can be explained on the basis of the reaction mechanism depicted in Scheme 5.3. The main catalytic cycle involves three successive forms of the enzyme in which the iron porphyrin prosthetic group undergoes changes in the iron oxidation state and the coordination sphere. E is a simple iron(III) complex. Upon reaction with hydrogen peroxide, it is converted into a cation radical oxo complex in which iron has a formal oxidation number of 5. This is then reduced by the reduced form of the cosubstrate, here an osmium(II) complex, to give an oxo complex in which iron has a formal oxidation number of 4. 

Proteins with molecular weights in the millions are the major constituents of all living cells. Simple proteins are hydrolyzed only to amino acids. Coqjugated proteins are hydrolyzed to amino acids and nonpeptide substances known as prosthetic groups. These prosthetic groups include nucleic acids of nucieoproteins, carbohydrates of glycoproteins, pigments (such as hemin and chiorophyli) of chromoproteins, and fats or lipids of lipoproteins. 

It is important to keep in mind that hydrophilic prosthetic groups are important for renal rather than hepatobiliary clearance. Wester et al. [62] have demonstrated this with their carbohydrated analogs. Since 18F possesses inherent imaging advantages, the development of a simple and rapid synthesis which will enable 18F-SSTr ligands to be clinically practical is also important. 

These are simple proteins combined with some non-protein substances known as prosthetic groups. The nature of the non-protein or prosthetic groups is the basis for the sub classification of conjugated proteins. 

Nucleoproteins are simple basic proteins (protamines or histones) in salt combination with nucleic acids as the prosthetic group. They are the important constituents of nuclei and chromatin. 

Molecular weight calculations from amino acid or prosthetic group analysis is based on the simple fact that there must be at least one mole of any residue present per mole of protein. There may be more than one mole of any given residue present. Thus, this method yields a minimum molecular weight,... 

Table 3 describes the basic iron-sulfur structures and the oxidation states that can be found in simple proteins and how they may associate with other prosthetic groups. 

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