Studies on the active centre of Rhodotorula gracilis D-amino acid oxidase and comparison with pig kidney enzyme.

نویسندگان

  • L Pollegioni
  • S Ghisla
  • M S Pilone
چکیده

D-Amino acid oxidase (EC 1.4.3.3) from Rhodotorula gracilis has been reconstituted with 8-chloro-, 8-mercapto-, 6-hydroxy-, 2-thio-, 5-deaza- and 1-deaza-FAD, and the properties of the resulting complexes have been studied and compared with those of the correspondingly modified pig kidney D-amino acid oxidases. Binding appears to be tight for most analogues, at least as tight as for native FAD (approximately 10(-8) M). 8-Mercapto- and 6-hydroxy-FAD bind in their para- and ortho-quinoid forms respectively to yeast D-amino acid oxidase, inferring the presence of a positive charge near the flavin N(1) position, as in the case of the mammalian enzyme. On the other hand, important differences in active-site microenvironment emerge: solvent accessibility to flavin position 8 is drastically restricted in yeast D-amino acid oxidase as indicated by the unreactivity of 8-chloro- and 8-mercapto-FAD enzyme with thiolates and alkylating agents. Significantly different microenvironments are also likely to occur around the flavin positions N(1)-C(2) = 0, N(3)-H and N(5). This is deduced from the differences in interaction of the two proteins with 1-deaza-FAD, 5-deaza-FAD and 2-thio-FAD and from the properties of the respective complexes. The same re-side flavin stereospecificity as shown by the mammalian enzyme was determined for the yeast enzyme using 8-hydroxy-5-deaza-FAD. Thus we can deduce the presence of a similar pattern of functional groups at the active centres of the two enzymes, while the fine tuning of specificity and regulation correlate with environmental differences at specific flavin loci.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

FAD ANALOGUES AS ACTIVE SITE PROBES OF Rhodotorula gracilis D-AMINO ACID OXIDASE

The wide range of chemical reactivity exhibited by flavoprotein enzymes is determined fundamentally by the nature of the protein moiety. Studies on the interactions of the isoalloxazine nucleus of flavin with the enzyme are therefore ~ important in understanding this reactivitYi flavin analogues are extremely useful probes for elucidating structure-function relationships (1, 2). We have used a ...

متن کامل

Studies on the Reaction Mechanism of Rhodotorula gracilis

We have studied D-amino-acid oxidase from Rhodotorula gracilis by site-directed mutagenesis for the purpose of determining the presence or absence of residues having a possible role in acid/base catalysis. Tyr-223, one of the very few conserved residues among D-aminoacid oxidases, has been mutated to phenylalanine and to serine. Both mutants are active catalysts in turnover with D-alanine, and ...

متن کامل

Chemical mechanism of D-amino acid oxidase from Rhodotorula gracilis: pH dependence of kinetic parameters.

The variation of kinetic parameters of d-amino acid oxidase from Rhodotorula gracilis with pH was used to gain information about the chemical mechanism of the oxidation of D-amino acids catalysed by this flavoenzyme. d-Alanine was the substrate used. The pH dependence of Vmax and Vmax/Km for alanine as substrate showed that a group with a pK value of 6.26-7.95 (pK1) must be unprotonated and a g...

متن کامل

Identification and role of ionizing functional groups at the active center of Rhodotorula gracilis D-amino acid oxidase.

D-Amino acid oxidase (DAAO) is a flavoprotein oxidase that catalyzes the oxidation of amino acids and produces ketoacids and H(2)O(2). The rate of product release from reduced DAAO from Rhodotorula gracilis is pH dependent and reflects a pK(a) of approximately 9.3. Binding of benzoate and 3,3,3-trifluoro-D-alanine to wild-type and Y238F-DAAO is also pH dependent (pK(a)=9.8+/-0.1 and 9.05+/-0.1,...

متن کامل

On the mechanism of Rhodotorula gracilis D-amino acid oxidase: role of the active site serine 335.

Serine 335 at the active site of D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO) is not conserved in other DAAO sequences. To assess its role in catalysis, it was mutated to Gly, the residue present in mammalian DAAO, an enzyme with a 35-fold lower turnover number with D-alanine. The spectral and ligand binding properties of the S335G mutant are similar to those of wild-type e...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • The Biochemical journal

دوره 286 ( Pt 2)  شماره 

صفحات  -

تاریخ انتشار 1992