Exploring the Kinetics and Thermodynamics of a Novel Histidine Ammonia-Lyase from .

Histidine ammonia-lyase (HAL) plays a pivotal role in the non-oxidative deamination of L-histidine to produce -urocanic, a crucial process in amino acid metabolism. This study examines the cloning, purification, and biochemical characterization of a novel HAL from (HAL) and eight active site mutants to assess their effects on substrate binding, catalysis, thermostability, and secondary structure. The HAL enzyme was successfully overexpressed and purified to homogeneity.

Efficiency Assessment between Entrapment and Covalent Bond Immobilization of Mutant β-Xylosidase onto Chitosan Support.

The Y509E mutant of β-xylosidase from (XynB2) (which also bears xylanase activity) has been immobilized in chitosan spheres through either entrapment or covalent bond formation methods. The maximum immobilization yield by entrapment was achieved by chitosan beads developed using a 2% chitosan solution after 1 h of maturation time in CFG buffer with ethanol. On the other hand, the highest value in covalent bond immobilization was observed when employing chitosan beads that were prepared from a 2% chitosan solution after 4 h of activation in 1% glutaraldehyde solution at pH 8.

Characterization of Cross-Linked Enzyme Aggregates of the Y509E Mutant of a Glycoside Hydrolase Family 52 β-xylosidase from .

Cross-linked enzyme aggregates (CLEAs) of the Y509E mutant of glycoside hydrolase family 52 β-xylosidase from with dual activity of β-xylosidase and xylanase (XynB2) were prepared. Ammonium sulfate was used as the precipitant agent, and glutaraldehyde as cross-linking agent. The optimum conditions were found to be 90% ammonium sulfate, 12.

Biochemical and Mutational Characterization of N-Succinyl-Amino Acid Racemase from Geobacillus stearothermophilus CECT49.

N-Succinyl-amino acid racemase (NSAAR), long referred to as N-acyl- or N-acetyl-amino acid racemase, is an enolase superfamily member whose biotechnological potential was discovered decades ago, due to its use in the industrial dynamic kinetic resolution methodology first known as "Acylase Process". In previous works, an extended and enhanced substrate spectrum of the NSAAR from Geobacillus kaustophilus CECT4264 toward different N-substituted amino acids was reported. In this work, we describe the cloning, purification, and characterization of the NSAAR from Geobacillus stearothermophilus CECT49 (GstNSAAR).

Enzymatic dynamic kinetic resolution of racemic N-formyl- and N-carbamoyl-amino acids using immobilized L-N-carbamoylase and N-succinyl-amino acid racemase.

Taking advantage of the catalytic promiscuity of L-carbamoylase from Geobacillus stearothermophilus CECT43 (BsLcar) and N-succinyl-amino acid racemase from Geobacillus kaustophilus CECT4264 (GkNSAAR), we have evaluated the production of different optically pure L-α-amino acids starting from different racemic N-formyl- and N-carbamoyl-amino acids using a dynamic kinetic resolution approach. The enzymes were immobilized on two different solid supports, resulting in improved stability of the enzymes in terms of thermostability and storage when compared to the enzymes in solution. The bienzymatic system retained up to 80% conversion efficiency after 20 weeks at 4 °C and up to 90% after 1 week at 45 °C.