Cysteamine-S-phosphate

Neumann (124) showed that cysteamine S-phosphate, aminoethanol O-phosphate, and serine O-phosphate could serve as phosphate sources for the various acceptors listed in Table IX without changing the percent transphosphorylated product formed for a given acceptor. Barrett et al. (121) found similar results for nine different substrates with tris acting as an acceptor. As previously stated, these results prove that a phosphoryl enzyme intermediate occurs. 

In contrast to the O-substituted monoesters, S-substituted phosphates (S—P bond in RSPO Na2), e.g., cysteamine S-phosphate, are hydrolyzed at a rate comparable to that of PNPP (32). 

Immobilization of cysteamine hydrochloride onto poly(oxyethylene phosphate)s... 

General procedure for the immobilization of cysteamine aminohydrochlorides onto polyialkylene phosphate)s ref J. Med. Chem. 2002,45, 5797). 

Coenzyme form(s). (1) Coenzyme A, composed of cysteamine, pantothenic acid, phosphate, and adenosine-3, 5 -diphosphate (2) acyl-carrier protein. 

Incubation of HPMA copolymers with purified lysosomal enzymes should help identify the enzyme(s) most active in side-chain degradation. Recently it has been found that incubation of cathepsin B with HPMA copolymers bearing oligopeptidyl side-chains terminating in p-nitroaniline (incubated in phosphate buffer (O.IM) pH 6.0 containing cysteamine (25mM) and EDTA (ImM) causes p-nitroaniline liberation from many sequences.The side-chain most susceptible to cleavage by tritosomes (26) is certainly very effectively hydrolysed by cathepsin B. ... 

Cysteamine oxygenase actl ty was determined as previously reported (30) with 2 jjmoles of S-cysteamine, in the presence or absence of 0.2 jjmoles of phenazine methosulfate as cofactor, with 100 umoles of phosphate buffer pH 7.6, in a final volume of 2 ml. After treatment with TCA aliquots were subjected to chromatography in Whatman n 4 paper strip by use of water-saturated phenol as solvent. Radioactivity was determined with a Packard 7201 radiochromatogram scanner and quantitative values were calculated by integration of radioactive peaks. 

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