Braun, O; Knipp, M; Chesnov, S; Vasák, M (2007). Specific reactions of S-nitrosothiols with cysteine hydrolases: A comparative study between dimethylargininase-1 and CTP synthetase. Protein Science, 16(8):1522-1534.
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S-Transnitrosation is an important bioregulatory process whereby NO(+) equivalents are transferred between S-nitrosothiols and Cys of target proteins. This reaction proceeds through a common intermediate R-S-N(O(-))-S-R' and it has been proposed that products different from S-nitrosothiols may be formed in protein cavities. Recently, we have reported on the formation of such a product, an N-thiosulfoximide, at the active site of the Cys hydrolase dimethylargininase-1 (DDAH-1) upon reaction with S-nitroso-l-homocysteine (HcyNO). Here we have addressed the question of whether this novel product can also be formed with the endogenously occurring S-nitrosothiols S-nitroso-l-cysteine (CysNO) and S-nitrosoglutathione (GSNO). Further, to explore the reason responsible for the unique formation of an N-thiosulfoximide in DDAH-1 we have expanded these studies to cytidine triphosphate synthetase (CTPS), which shows a similar active site architecture. ESI-MS and activity measurements showed that the bulky GSNO does not react with both enzymes. In contrast, S-nitrosylation of the active site Cys occurred in DDAH-1 with CysNO and in CTPS with CysNO and HcyNO. Although kinetic analysis indicated that these compounds act as specific irreversible inhibitors, no N-thiosulfoximide was formed. The reasons likely responsible for the absence of the N-thiosulfoximide formation are discussed using molecular models of DDAH-1 and CTPS. In tissue extracts DDAH was inhibited only by HcyNO, with an IC(50) value similar to that of the isolated protein. Biological implications of these studies for the function of both enzymes are discussed.
|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||04 Faculty of Medicine > Functional Genomics Center Zurich|
08 University Research Priority Programs > Systems Biology / Functional Genomics
|DDC:||570 Life sciences; biology|
610 Medicine & health
|Deposited On:||28 Dec 2009 08:34|
|Last Modified:||23 Nov 2012 16:27|
|Free access at:||Publisher DOI. An embargo period may apply.|
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