ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Interaction of high-affinity nucleotide binding sites in mitochondrial ATP synthesis and hydrolysis (1982)

Schäfer, G. ; Weber, J.

Springer

Journal of bioenergetics and biomembranes 14 (1982), S. 479-498

add to mindlist on the mindlist

Details

ISSN: 1573-6881

Keywords: Oxidative phosphorylation ; F1-ATPase ; nucleotide binding sites ; cooperativity ; nucleotide analogs ; fluorescence ; mechanism

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Physics

Notes: Abstract The present study contributes to the problem of the dynamic structure of mitochondrial F1-ATPase and the functional interrelation of so-called tight nucleotide binding sites. Nucleotide analogs are used as a tool to differentiate two distinct functional states of the membrane-bound enzyme, proposed to reflect corresponding conformational states; they reveal F1-ATPase as a “dual-state” enzyme: ATP-synthetase, and ATP-hydrolase. The analogs used are 3′-naphthoyl esters of AD(T)P, and 2′(3′)-O-trinitrophenyl ethers of AD(T)P. Both types of analogs act inversely to each other with respect to their relative effects on oxidative phosphorylation and on ATPase in submitochondrial vesicles. The respective ratios ofK i versus both processes are 250/1 compared to 1/170. It is also shown that in the presence of the inhibitory 3′-esters oxidative phosphorylation deviates from linear kinetics and that these inhibitors induce a lag time of oxidative phosphorylation depending on the initial pattern of nucleotides available to energized submitochondrial vesicles. The duration of the lag time coincides with the time course of displacement of the analog from a tight binding site. The conclusions of the study are: (a) the catalytic sites of F1-ATP-synthetase are not operating independently from each other; they rather interact in a cooperative manner; (b) F1-ATPase as a “dual-state” enzyme exhibits highly selective responses to tight binding of nucleotides or analogs in its “energized” (membrane-bound) state versus its “nonenergized” state, respectively.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00743073

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Das Verhalten rostfreier Stahlgußlegierungen unter gleichzeitiger mechanischer und korrosiver Belastung (1980)

Heitz, E. ; Litzkendorf, M. ; v. Meysenbug, C.-M. ; [et al.]

Weinheim : Wiley-Blackwell

Materialwissenschaft und Werkstofftechnik 11 (1980), S. 244-258

add to mindlist on the mindlist

Details

ISSN: 0933-5137

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Description / Table of Contents: Behaviour of stainless cast alloys under combined mechanical and corrosive attackIn media with 3000 mg B/1 (as boric acid, H3BO3) and varying chloride contents down to 1 mg Cl-/1 13%-Cr-steels show pitting. Under constant load cracks appear simultaneously. As can be expected, 17%-Cr-steels are more resistant and duplex ferritic austenitic steels exhibit no corrosion cracking in 3% NaCl-solution even after 10 000 hrs. Generally, corrosion resistance improves with increasing contents of ferrite forming elements. Corrosion cracks are interpreted in termes of anodic stress corrosion cracking. Notch impact bending tests with hydrogen charged specimens show that deformability is reduced.

Notes: 13%-Cr-Stähle zeigen in Lösungen mit 3000 mg B/1 (als Borsäure, H3BO3) und unterschiedlichen Chloridgehalten Lochkorrosion bis herab zu Konzentrationen von 1 mg Cl-/1. Bei mechanischer Zugbeanspruchung treten gleichzeitig Risse auf. 17%-Cr-Stähle sind erwartungsgemäß beständiger und ferritisch-austenitische Stähle zeigen in 3% NaCl-Lösung auch im 10 000 h-Versuch keine Korrosionsrisse. Generell steigt die Beständigkeit mit zunehmendem Anteil an ferritbildenden Elementen. Die Korrosionsrisse werden als anodische Spannungsrißkorrosion interpretiert. Kerbschlagbiegeversuche mit wasserstoffbeladenen Proben ergeben eine Abnahme des Verformungsvermögens.

Additional Material: 21 Ill.