Abstract: New mutant .beta.-lactam Penicillin G acylases are provided, exhibiting altered substrate specificities. These Penicillin G acylases are obtained by expression of a gene encoding said Penicillin G acylase and having an amino acid sequence which differs at least in one amino acid from the wild-type Penicillin G acylase.

Abstract: The present invention provides for a non-nickel-containing catalyst which is effective for use in the production of dimer products and higher olefin products from a butene starting material at relatively high conversion, good selectivity towards octene production and good activity maintenance over prolonged polymerization times. The catalyst is prepared by impregnating an amorphous trivalent metal oxide support selected from the group consisting of aluminum oxide, gallium oxide and indium oxide with a silicon-containing precursor compound which, after calcination, yields a substantial mono layer of SiO.sub.2 on the surface of the metal oxide support. A disperse layer of TiO.sub.2 is then deposited on the surface of the SiO.sub.2 monolayer by application of a solvent solution of a precursor compound containing titanium onto the SiO.sub.2 monolayer, followed by calcination to reduce the precursor titanium compound to TiO.sub.2.