PubMed · 1128406
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
W Poser, S Poser. 1975-02-15. Letter: Bromide abuse.. https://pubmed.ncbi.nlm.nih.gov/1128406/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The reaction of 1-(2,3-anhydro-5-O-trityl-beta-D-lyxofuranosyl)-2-O-methyluracil (1a) and its thymine analogue (1b) with dilithium tetrahalocuprate (Li2CuX4) revealed excellent to perfect regioselectivity, yielding 2,2'-anhydro-3'-halonucleosides (2a-d), while the same reactions with 2,3-anhydro uracil and thymine nucleosides (4a,b) gave arabinosyl (5a-d) and xylosyl halohydrins (6a-d) with the respective product ratio of 7:3 to 8:2. compounds 5 and 6 were isolated as the 2-O-(7) and 3- O-mesyl derivatives (8).
Origins of CD bands in lima bean proteinase inhibitor were deduced from an acetylation-deacetylation study of the sole tyrosyl residue in the protein (Tyr 69), and by analogy with Bowman-Birk soybean proteinase inhibitor, a homologous protein with similar spectral properties. Tyr 69 is relatively inaccessible to N-acetylimidazole; 100-fold molar excess of the reagent in the presence of 6 M guanidine hydrochloride elicited about 70 to 80% O-acetylation. A broad negative CD band centered around 280 nm arises mainly from the longest wavelength transition of cystinyl side chains (epsilon L--epsilon R approximately equal to -0.8 M-1 cm-1 per disulfide). The second cystinyl transition gives rise to a positive CD band of a comparable intensity at 247 nm. The Lb vibronic transition of Tyr 69 has negative CD around 280 nm, contributing approximately 10% of the total CD intensity at 278 nm (epsilon L--epsilon R approximately equal to -0.5 M-1 cm-1). The 232 nm positive shoulder is from the La vibronic transition of Tyr 69. Radical anions, Br2- and (CNS)2-, generated by the irradiation of N2O-saturated inhibitor solutions containing KBr or KCNS, reduced tyrosyl CD without affecting disulfide CD bands, indicating that the radical anions damaged Tyr 69 without altering protein conformation. The inhibitor modified at Tyr 69 by Br2- and (CNS)2- retained full activity toward trypsin and chymotrypsin. The irradiation of the inhibitor in the air-saturated solution led to loss in tyrosyl as well as cystinyl CD bands and decline in both antiproteinase activities.
Explore the source record for details and available documents.