Reference

Synthesis and enzymic degradation of depsipeptide copolymers

Synthesis and enzymic degradation of depsipeptide copolymers. Shirahama, Hiroyuki; Umemoto, Kouichi; Yasuda, Hajime (Dep. Applied Chem., Hiroshima Univ., Higashi-Hirohima 739, Japan). Kobunshi Ronbunshu, 54(1), 1-9 (Japanese) 1997 Kobunshi Gakkai. CODEN: KBRBA3. ISSN: 0386-2186. DOCUMENT TYPE: Journal CA Section: 35 (Chemistry of Synthetic High Polymers) Section cross-reference(s): 7, 34 A cyclic depsipeptide, 3,6-dimethyl-2,5-morpholinedione (DMO), was synthesized from DL-alanine (amino acid) and DL-2-bromopropionyl bromide (hydroxy acid deriv.). Then, DMO homopolymers and copolymers of DMO with lactones [(R)-3-methyl-4-oxa-6-hexanolide ((R)-MOHEL, an optically active new lactone), d-valerolactone (VL), and e-caprolactone (CL)] were prepd. by ring-opening polymn. using tin(II) octylate as a catalyst, and the enzymic degradability of these copolymers was examd. The DMO homopolymers with the no. av. mol. wt. (Mn) >3 ′ 103 could not be obtained. The DMO/lactone copolymers with Mn f 2 ′ 104 were obtained when the DMO content in the polymer was <10 mol%. In particular, it was possible to prep. DMO/CL copolymer with 2 ′ 104 < Mn < 6 ′ 104 over a relatively wide range of DMO content (0-30 mol%). The measurements of thermal properties and NMR for these copolymers revealed that the polymers obtained were random copolymers. 7365-44-8 and 9002-07-7 which are cas registry numbers of substances are two of reagents here. The enzymic degrdn. of DMO/VL and DMO/CL copolymers (Mn > 1 ′ 104) was studied by using proteases (carboxypeptidase A, trypsin, proteinase K) and (cholesterol) esterase. Proteinase K and the esterase degraded these copolymers greatly. Some (thermal) properties of the copolymers and the substrate specificity of the enzymes probably affected these degrdn. results. .

The use of hydrophilic counterion for superior retention and separation of anionic metal chelates in reversed-phase partition high performance liquid chromatography

The use of hydrophilic counterion for superior retention and separation of anionic metal chelates in reversed-phase partition high performance liquid chromatography. Kaneko, Emiko; Noda, Hiroyuki; Hoshino, Hitoshi; Yotsuyanagi, Takao (Dep. Appl. Chem., Tohoku Univ., Sendai 980-77, Japan). Chemistry Letters, (12), 1045-1046 (English) 1996 Nippon Kagakkai. CODEN: CMLTAG.In this article, certain chemicals are used. Some of their cas registry numbers are 77-86-1 and 7365-44-8 ISSN: 0366-7022. DOCUMENT TYPE: Journal CA Section: 79 (Inorganic Analytical Chemistry) Hydrophilic ions, such as protonated tris(hydroxymethyl)aminomethane (H+THMAM), are eminently suitable as counterion for reversed-phase partition HPLC. The anionic metal chelates with 2,2'-dihydroxyazobenzene were sepd. on C18-bonded silica packing with an aq. methanol mobile phase (pH 7.9) contg. THMAM, and detected spectro-photometrically. .