Title

NUCLEOTIDE CYCLASES AND CYCLIC NUCLEOTIDE BINDING PROTEINS IN MYXOCOCCUS XANTHUS.

Date of Award

1982

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biological Sciences

Keywords

Chemistry, Biochemistry.

Rights

CC BY-NC-ND 4.0

Abstract

Myxococcus xanthus vegetative cells contained significant amounts of nucleotide cyclase activities and cyclic neucleotide binding proteins. The guanylate cyclase activity was distributed between the 100,000g supernatant and pellet fractions, required divalent cation and exhibited an apparent K(,m) of 1.0mM. Adenylate cyclase activity was detected both in the 100,000g supernatant and pellet. The supernatant enzyme had an apparent K(,m) of 220(mu)M with a Hill coefficient of 1.9, whereas that of pellet fraction had an apparent K(,m) of 72(mu)M and a Hill coefficient of 1.0. The enzymes differed in their pH optima and divalent cation requirements. Three binding activities, one specific for guanosine 3',5'-monophosphate (cGMP) and two specific for adenosine 3',5'-monophosphate (cAMP) have been partially purified. The cylic GMP binding activity exhibited high specificity and affinity towards cGMP with a K(,D) of 42nM. Scatchard analysis of the data indicated a single class or binding sites. The two cAMP binding activities were physically distinct as indicated by their cellular locations and dissociation constants. The cytoplasmic binding protein exhibited a K(,D) of 57nM whereas that of the periplasm had a lower affinity with a K(,D) of (mu)M. During development, the nucleotide cyclases and cyclic nucleotide binding proteins exhibited changes in activities that are consistent with the previous proposal for the involvement of cyclic nucleotides in development (McCurdy, Ho and Dobson, 1978).Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1982 .D495. Source: Dissertation Abstracts International, Volume: 43-07, Section: B, page: 2186. Thesis (Ph.D.)--University of Windsor (Canada), 1982.