PubMed Health⌕ Search

PubMed · 7597635

Photosystem I: Structural and functional studies.

Abstract

In this article we describe the current knowledge of the structure of photosystem I, in particular the cyanobacterial form of this photosynthetic complex. We also describe recent experiments on the stability of the complex in detergents and denaturants and discuss the results in relation to the functional properties of the complex in electron transport across the thylakoid membrane.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

R C Ford, J Howson. 1994. Photosystem I: Structural and functional studies.. https://pubmed.ncbi.nlm.nih.gov/7597635/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Hydrogen embrittlement of work-hardened Ni-Ti alloy in fluoride solutions.

Hydrogen embrittlement of work-hardened Ni-Ti alloy has been examined in acidulated phosphate fluoride (APF) solutions. Upon immersion in a 2.0% APF solution with a pH of 5.0, tensile strength decreased markedly with immersion time. Moreover, the fracture mode changed from ductile to brittle due to brittle layer formation at the peripheral part of the cross section of the specimen. The amount of absorbed hydrogen increased linearly with immersion time, and it reached above 5000 mass ppm after 24 h. The hydrogen desorption temperature of the immersed specimens shifted from 450 degrees C to a lower temperature with immersion time. As the amount of absorbed hydrogen was larger than 500 mass ppm, the degradation of mechanical properties was recognized. Although the tensile properties and fracture mode scarcely change in a 0.2% APF solution, the slight reduction in hardness and hydrogen absorption of several hundreds mass ppm were observed. The results of the present study imply that work-hardened Ni-Ti alloy is less sensitive to hydrogen embrittlement compared with Ni-Ti superelastic alloy.

Absorption↗

Synthesis and evaluation of 6-methylene-bridged uracil derivatives. Part 1: discovery of novel orally active inhibitors of human thymidine phosphorylase.

A series of novel 6-methylene-bridged uracil derivatives have been prepared as inhibitors of human thymidine phosphorylase (TP). To enhance the in vivo antitumor activity of fluorinated pyrimidine 2'-deoxyribonucleosides such as 2'-deoxy-5-(trifluoromethyl)uridine (F(3)dThd), a potent TP inhibitor preventing their degradation to an inactive compound, has become a target of medicinal chemistry. We present here the synthesis and evaluation of novel human TP inhibitors. Introduction of an N-substituted aminomethyl side chain at the 6-position of 5-chlorouracil has improved water solubility and enhanced inhibitory activity compared with the known TP inhibitor, 6-amino-5-chlorouracil. Compound 42 was reasonably well absorbed in mice after oral administration. When combined with F(3)dThd, compound 42 exerted its TP inhibitory potency by increasing the maximum plasma concentrations of the former as evidenced in experiments with monkeys. Positive changes in pharmacokinetic profile were accompanied by the enhanced in vivo antitumor activity of this combination when compared to F(3)dThd alone, in mice bearing human tumor xenografts. Both biochemical and pharmacological effects appeared to fit the concept as anticipated.

Absorption↗

Synthesis and evaluation of 6-methylene-bridged uracil derivatives. Part 2: optimization of inhibitors of human thymidine phosphorylase and their selectivity with uridine phosphorylase.

A series of novel 6-methylene-bridged uracil derivatives have been optimized for clinical use as the inhibitors of human thymidine phosphorylase (TP). We describe their synthesis and evaluation. Introduction of a guanidino or an amidino group enhanced the in vitro inhibitory activity of TP comparing with formerly reported inhibitor 1. Their selectivity for TP based on uridine phosphorylase inhibitory activity was also evaluated. Compound 2 (TPI) has been selected for clinical evaluation based on its strong TP inhibition and excellent modulation of 2'-deoxy-5-(trifluoromethyl)uridine (F(3)dThd) pharmacokinetics. As a result, TAS-102 (a combination of F(3)dThd and TPI) is currently in phase 1 clinical studies.

Absorption↗