Week 1 overview




Cystathionine b-lyase (CBL) is a bacterial enzyme catalyzing the penultimate step in the pyridoxyl 5'-phosphate (PLP) dependent hydrolysis of L-cystathionine to L-homocysteine, pyruvate and ammonia [1] (Scheme 1).










Pyridoxyl 5-phosphate


There is a strong clinical correlation between defects in the mammalian homologue, cystathionine g-lyase, and the formation of arteriosclerotic plaques [2]. This connection makes our study of the bacterial system interesting as we apply, in principle, what we learn to a pertinent problem in current clinical biochemistry.









One advantage of working with cystathionine b-lyase in a laboratory setting is the enzymatic reactions are robust, reproducible and can be monitored in real time by visible spectroscopy [3]. Having a functional kinetics assay at the core of this course will allow us to explore additional aspects of enzymology including purification (affinity versus size exclusion chromatography), mutations (molecular biology and bioinformatics applications), active site modeling, reaction mechanisms and inhibition (molecular modeling, organic chemistry).




1. Laber, B., et al., Cloning, purification, and crystallization of Escherichia coli cystathionine beta-lyase. Febs Letters, 1996. 379(1): p. 94-96.

2. Steegborn, C., et al., Kinetics and inhibition of recombinant human cystathionine gamma-lyase - Toward the rational control of transsulfuration. Journal of Biological Chemistry, 1999. 274(18): p. 12675-12684.

3. Uren, J.R., Cystathionine Beta-Lyase From Escherichia-Coli. Methods In Enzymology, 1987. 143: p. 483-486.