Advanced studies on cyclic amino acids in neurological signaling and peptide antibiotics
many organisms, including primates, as an intermediate in lysine degradation. The
pathway by which lysine is converted into L-pipecolic acid employs the enzyme Lpipecolate
oxidase (L-PO), and appears to be tissue specific to the central nervous system
(CNS). The oxidation facilitated by L-PO is the rate limiting step of lysine degradation
in the CNS. For this reason, the mechanism of action for L-PO may be useful in the
development of neuromodulation. This thesis describes efforts to probe the mechanism
of action of L-PO through the synthesis of substrate analogs as alternate substrates and
inhibitors of L-PO.
Analogs that contain heteroatoms and other functionalities at key positions have
been synthesized and analyzed as both alternate substrates and inhibitors of L-PO. The
4,5-methanopipecolic acid has been shown to be an excellent substrate for L-PO. The 5-
keto analog was not a substrate or inhibitor of the enzyme. The 5-hydroxy and 5,5-
difluoro analogs have been shown to be weak inhibitors of L-PO. 6S-methyl-L-pipecolic
acid (35) was shown to be a weak substrate and strong inhibitor while the enantiomeric
6R methyl-D-pipecolic acid (36) was neither a substrate nor inhibitor.
These results suggest flexibility within the binding pocket of L-pipecolate oxidase
toward analogs containing substituents at the 5-position. Additionally, these studies
demonstrate the potential to develop mechanism-based inhibitors that could be used to
control the rate of L-pipecolic acid consumption as well as the production of downstream
A hallmark of peptide antibiotics are the varied and unique amino acids they
employ. Capreomycidine and enduracididine are two such examples found in the peptide
antibiotics muraymycin and enduracidin, respectively. Both are cyclic amino acids
derived from arginine.
Muraymycin is produced by Streptomyces sp. 30471 and has been shown to be
active against a number of Gram-positive bacteria including Methicillin-resistant
Staphylococcus aureus (MRSA). In an effort to further our understanding of this
antibiotic, efforts to isolate the muraymycin gene cluster have begun. A genomic library
has been constructed in the pCCFos1 Copy Control vector. Efforts to identify the genes
encoding for the enzyme involved in the conversion of L-arginine to capreomycidine are
Enduracidin is another peptide antibiotic which contains a cyclized form of
arginine, enduracididine. Enduracidin has potent activity against Gram-positive bacteria
including Methicillin-resistant Staphylococcus aureus. The enduracidin gene cluster has
been cloned and sequenced by Yin and Zabriskie . Efforts to express and characterized
the genes involve in the biosynthesis of enduracididine are described. Labeled feeding
studies were also employed to determine the precursor to enduracididine. ¹³C-?-hydroxyarginine was synthesized and ?- and ?-hydroxyarginine were used in feeding
experiments to determine which, if either, would be incorporated into enduracidin.
Labeled enduracidin was isolated and characterized by LC-MS from feeding studies
using ¹³C-?-hydroxyarginine, identifying ?-hydroxyarginine as a precursor to
Additional studies were performed using 3-fluoro-L-tyrosine. The fluoro-tyrosine
was converted to 3-fluoro-4-hydroxyphenylglycine through a pathway utilized for
hydroxyphenylglycine biosynthesis. The 3-fluoro-4-hydroxyphenylglycine was found to
be incorporated into multiple positions within enduracidin by LC-MS.
Advisor:Zabriskie, T. Mark; Proteau, Philip, J.; Mahmud, Taifo; Yin, Xihou; Savage, Thomas, F.
School:Oregon State University
School Location:USA - Oregon
Source Type:Master's Thesis
Keywords:enduracidin muraymycin capreomycin lysine pipecolate pipecolic acid peptide antibiotic antibiotics development anticonvulsants neural transmission oxidoreductases inhibitors gaba amino neurotransmitters
Date of Publication:03/18/2008