36360-61-9Relevant articles and documents
Transformation of gold(I)-cyclo[-Met-Met-] complex supramolecular fibers into aligned gold nanoparticles
Furutani, Masahiro,Kudo, Kazuaki
, p. 601 - 603 (2013)
A cyclic dipeptide cyclo[L-methionylL- methionyl] and gold(I) cation were found to form a complex in a 1:2 ratio. Pouring a DMF solution of the complex into ethyl acetate afforded fibers with lengths of more than 20 μm and 100400nm in width, which consisted of fibrous nanostructures 50100nm in diameter. Treatment of this supramolecular fiber with catechol gave linearly aligned Au nanoparticles on the original fibers.
Stabilized analogs of thymopentin. 1. 4,5-Ketomethylene pseudopeptides
DeGraw, Joseph I.,Almquist, Ronald G.,Hiebert, Charles K.,Colwell, William T.,Crase, Jac,Hayano, Takeshi,Judd, Amrit K.,Dousman, Linda,Smith, R. Lane,Waud, William R.,Uchida, Itsuo
, p. 2386 - 2397 (2007/10/03)
The pentapeptide, thymopentin (Arg1-Lys2-Asp3-Val4-Tyr5) is known for its activity as an immunomodulating drug, but with limited half-life in plasma. In this first paper of a series of three studies, the synthesis of analogs stabilized at the peptide bond between the C-terminal amino acids via insertion of a ketomethylene moiety is described. N-Blocked pseudopeptides containing Val(k)Phe, Ala(k)Phe, and Val(k)Val units were prepared and attached to chloromethyl Merrifield resin via the carboxy terminal. Removal of the N-BOC group by trifluoroacetic acid was followed by sequential coupling with N-BOC dipeptides of aspartic acid to yield resin-bound N-BOC pseudotetrapeptides. Removal of N-BOC and coupling with N-BOC-r-N- tosylarginine followed by total cleavage of blocking groups and resin by HF afforded the target pseudopentapeptides. The analogs were found to compete favorably with thymopentin for binding to CEM cells, but binding was reduced by about 20-30% on average. All analogs showed significant enhancement of half-life versus thymopentin in mouse serum, but most showed only modest improvement in human serum. Insertion of proline or norleucine at position 2 in the chain caused a substantial increase in half-life (3-4-fold), while N- methylnorleucine conferred complete stability in the analogs.
Specificity of lysine: N6-hydroxylase: A hypothesis for a reactive substrate intermediate in the catalytic mechanism
Marrone,Siemann,Beecroft,Viswanatha
, p. 401 - 416 (2007/10/03)
The recombinant cytoplasmic preparation of lysine: N6-hydroxylase catalyzes the conversion of L-lysine to its N6-hydroxy derivative when supplemented with the cofactors NADPH and FAD. A number of lysine analogs reflecting minor alterations in the inherent structural features of the amino acid as well compounds with relatively high affinity for lysine binding domains in other proteins were examined for their ability to serve as substrates of lysine: N6-hydroxylase. These studies have revealed that the enzyme does not tolerate any change in the structural features of L-lysine, its preferred substrate, with the exception of the replacement of the C(γ)H2-methylene group by sulfur, as in (S)-2-aminoethyl-L-cysteine. L-Norleucine is a potent inhibitor of the enzyme while L-norvaline and L-α-aminobutyric acid do not exhibit such effect, indicating the importance of a C4 hydrophobic side chain for effective interaction with the enzyme. Among the N-alkyl amides of hydrophobic amino acids, only L-norleucine methylamide and L-α-aminobutyric acid ethylamide serve as moderate inhibitors of lysine: N6-hydroxylase. Based on the enzyme's stringent substrate specificity, a mechanism involving the conversion of L-lysine to 2-aminocaprolactam prior to its oxygenation by the 4α-peroxyflavin intermediate in the catalytic cycle is proposed.
