Abstract: The invention discloses a series of Methanococcus jannaschii S-adenosylmethionine synthetase mutants with improved thermostability and high catalytic activity obtained by using gene mutation technique, characterized in that these mutants refer to an enzyme using Sequence 2 in the Sequence Listing as the reference sequence and contains at least one mutation at position 102, position 93, position 230, and position 357 and has a catalytic activity at least 70% higher than that of the wild-type S-adenosylmethionine synthetase using adenosine triphosphate (ATP) and methionine as substrates. These S-adenosylmethionine synthetase mutants can be used in the production of S-adenosylmethionine.

Abstract: The invention discloses a carrier made from an organic foam having open pores for enzymes or cells immobilization and the methods for preparing immobilized enzymes or cells. The invention uses flocculation and crosslinking technology to immobilize enzyme protein or cells on the organic foam material having open pores. The resultant immobilized products have larger specific surface area, higher specific activity and can be made into various shapes.

Abstract: The invention discloses a series of Methanococcus jannaschii S-adenosylmethionine synthetase mutants with improved thermostability and high catalytic activity obtained by using gene mutation technique, characterized in that these mutants refer to an enzyme using Sequence 2 in the Sequence Listing as the reference sequence and contains at least one mutation at position 102, position 93, position 230, and position 357 and has a catalytic activity at least 70% higher than that of the wild-type S-adenosylmethionine synthetase using adenosine triphosphate (ATP) and methionine as substrates. These S-adenosylmethionine synthetase mutants can be used in the production of S-adenosylmethionine.