Abstract: A mutant tyrosine repressor that does not require tyrosine to induce expression of tyrosine phenol-lyase gene is obtained by introducing a mutation into a tyrosine repressor. A microorganism which is able to express large amounts of tyrosine phenol-lyase is obtained by introducing the mutant tyrosine repressor into the microorganism. The microorganism is useful for producing L-DOPA.

Abstract: A mutant tyrosine repressor that does not require tyrosine to induce expression of tyrosine phenol-lyase gene is obtained by introducing a mutation into a tyrosine repressor. A microorganism which is able to express large amounts of tyrosine phenol-lyase is obtained by introducing the mutant tyrosine repressor into the microorganism. The microorganism is useful for producing L-DOPA.

Abstract: The present invention provides a transglycosylation method and a protein catalyzing a transglycosylation reaction. A reaction of transferring a galactosyl?1?3N-acetylgalactosaminyl group from a sugar donor containing a sugar chain having a galactosyl?1?3N-acetylgalactosaminyl group bound thereto at the ?-position, to a sugar chain acceptor, is carried out in the presence of a protein having an endo-?-N-acetylgalactosaminidase activity and a transglycosylation activity.

Abstract: A mutant tyrosine repressor that does not require tyrosine to induce expression of tyrosine phenol-lyase gene is obtained by introducing a mutation into a tyrosine repressor (tyrR), isolated from Pantoea agglomerans, or a tyrosine repressor (tyrR) which is encoded by SEQ ID NO. 1 and its derivative. A microorganism which is able to express large amounts of tyrosine phenol-lyase is obtained by introducing the mutant tyrosine repressor into the microorganism. The microorganism is useful for producing L-DOPA.

Abstract: The present invention provides a transglycosylation method and a protein catalyzing a transglycosylation reaction. A reaction of transferring a galactosyl?1?3N-acetylgalactosaminyl group from a sugar donor containing a sugar chain having a galactosyl?1?3N-acetylgalactosaminyl group bound thereto at the ?-position, to a sugar chain acceptor, is carried out in the presence of a protein having an endo-?-N-acetylgalactosaminidase activity and a transglycosylation activity.

Abstract: The present invention provides a transglycosylation method and a protein catalyzing a transglycosylation reaction. A reaction of transferring a galactosyl?1?3N-acetylgalactosaminyl group from a sugar donor containing a sugar chain having a galactosyl?1?3N-acetylgalactosaminyl group bound thereto at the ?-position, to a sugar chain acceptor, is carried out in the presence of a protein having an endo-?-N-acetylgalactosaminidase activity and a transglycosylation activity.

Abstract: A mutant tyrosine repressor that does not require tyrosine to induce expression of tyrosine phenol-lyase gene is obtained by introducing a mutation into a tyrosine repressor. A microorganism which is able to express large amounts of tyrosine phenol-lyase is obtained by introducing the mutant tyrosine repressor into the microorganism. The microorganism is useful for producing L-DOPA.

Abstract: A gene coding for a mutant tyrosine repressor having increased positive regulatory activity for expression of the tyrosine phenol lyase gene compared with a tyrosine repressor not having mutation is obtained by introducing a mutation into a tyrosine repressor gene of Erwinia herbicola, introducing the gene into which the mutation is introduced into Escherichia coli expressing a lactose operon under the control of a promoter and enhancer of the tyrosine phenol lyase gene derived from Erwinia herbicola, and selecting a transformed strain having increased ?-galactosidase activity.

Abstract: A gene coding for a mutant tyrosine repressor having increased positive regulatory activity for expression of the tyrosine phenol lyase gene compared with a tyrosine repressor not having mutation is obtained by introducing a mutation into a tyrosine repressor gene of Erwinia herbicola, introducing the gene into which the mutation is introduced into Escherichia coli expressing a lactose operon under the control of a promoter and enhancer of the tyrosine phenol lyase gene derived from Erwinia herbicola, and selecting a transformed strain having increased ?-galactosidase activity.

Abstract: An endo-&bgr;-N-acetylglucosaminidase gene encoding the following protein (a) or (b): (a) a protein comprising the amino acid sequence represented by SEQ ID NO: 3; and (b) a protein comprising an amino acid sequence derived from the amino acid sequence represented by SEQ ID NO: 3 by deletion, substitution, or addition of at least one amino acid and having the activity of endo-&bgr;-N-acetylglucosaminidase.

Abstract: A gene coding for a mutant tyrosine repressor having increased positive regulatory activity for expression of the tyrosine phenol lyase gene compared with a tyrosine repressor not having mutation is obtained by introducing a mutation into a tyrosine repressor gene of Erwinia herbicola, introducing the gene into which the mutation is introduced into Escherichia coli expressing a lactose operon under the control of a promoter and enhancer of the tyrosine phenol lyase gene derived from Erwinia herbicola, and selecting a transformed strain having increased &bgr;-galactosidase activity.

Abstract: Using as a host Escherichia coli which expresses lactose operon under the control of the promoter/enhancer of tyrosine phenol lyase gene derived from Erwinia herbicola, a DNA fragment coding for tyrosine repressor (tyrR) having an amino acid sequence depicted in SEQ ID NO: 2 in Sequence Listing is obtained from the chromosome gene library of Erwinia herbicola.

Abstract: This invention provides endo-.alpha.-N-acetylgalactosaminidase (endo-.alpha.-GalNAcase) from a microorganism belonging to the genus Alcarigenes. This endo-.alpha.-GalNAcase is very useful in the analysis of the structure and function of mucin-type sugar chains of glycoproteins, as it is an enzyme that cleaves O-glycosidic linkages of sugar chains of glycoproteins, releasing the sugar chain from said protein.

Abstract: L-cysteine and derivatives thereof of the formula (I): ##EQU1## wherein R is selected from the group consisting of hydrogen, C.sub.1 -C.sub.15 alkyl, C.sub.2 -C.sub.15 alkenyl, C.sub.6 -C.sub.15 aryl, C.sub.7 -C.sub.15 aralkyl, are prepared by a process which comprises reacting .beta.-substituted L-alanine having the formula (II): ##EQU2## wherein X is selected from the group consisting of halogen, --OR' and --SR'; wherein R' is selected from the group consisting of hydrogen, allyl, C.sub.1 -C.sub.15 alkyl, C.sub.6 -C.sub.15 aryl and C.sub.7 -C.sub.15 aralkyl, with a thiol, or hydrogen sulfide, of the formula (III):r -- sh (iii)wherein R is as defined above, ammonium hydrosulfide of a metal hydrosulfide of the formula (IV):r -- s --y (iv)wherein R is hydrogen, and Y is ammonium or a metal, in an aqueous medium, in the presence of cysteine desulfhydrase.