Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 54 (1998), S. 372-377 
    ISSN: 1420-9071
    Keywords: Key words. Protein folding; β-lactamase; cis-trans isomerization; folding intermediates; molten globule.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. This review traces some of the key features of the folding of β-lactamases and their relevance to the way proteins fold in general. Studies on the enzymes have highlighted the nature and role of equilibrium and transient condensed states. The kinetics of folding are multiphasic, and when monitored by acrylamide quenching of the tryptophan fluorescence, an early phase provides evidence for the transient accumulation of a nonnative intermediate involving burial of tryptophan in a nonpolar environment. Intermediate phases can be understood in terms of progressive folding of different parts of the molecule. The later, slow phases are associated with proline isomerization in the TEM-1 enzyme and, in its P167T mutant form, with isomerization from trans to cis of the E166 T167 peptide bond. Coupled with kinetic and X-ray crystallographic studies of the β-lactamase from Staphylococcus aureus and its D179Q mutant, it appears that the final stage of folding is that of collapse and packing of the Ω-loop on to the main body of the protein.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    Leiden : Periodicals Archive Online (PAO)
    Arabica. 39 (1992) 261 
    ISSN: 0570-5398
    Topics: Linguistics and Literary Studies , Ethnic Sciences , History , Theology and Religious Studies
    Notes: Bulletin Critique
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1076
    Keywords: Exercise testing ; Congenital heart disease ; Acrobic capacity ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aerobic capacity of patients with different forms of congenital heart disease was serially evaluated in 79 patients and the evolution was correlated with the lesion and the level of daily activity. The patients were divided into six groups: patients with a small ventricular septal defect (VSD) with mini shunt (n=14), mild pulmonary valve stenosis with gradient 〈40 mm Hg (PS) (n=12), mild to moderate aortic valve stenosis (gradient 36±17 mm Hg) (AS) (n=12), patients 4.7±2.1 years after repair of tetralogy of Fallot (PO-TF) (n=16), patients 2.2±2.9 years after closure of a high flow/high gradient VSD (PO-VSD) (n=13), and patients 2.6±1.7 years after Fontan repair (Fontan-PO) (n=12). Aerobic capacity was assessed by determination of the ventilatory anaerobic threshold (VAT). VAT reflects the highest aerobic exercise level prior to a disproportionate increase of CO2 and ventilation relative to O2 uptake; it is independent of patient motivation. Data are expressed as percentage of normal O2 uptake at VAT, determined in 234 age/gender matched controls. The habitual level of physical activity was assessed by a standardised questionnaire. Aerobic capacity in all subgroups of patients, even with very mild defects, was at or below the lower limit of normal. Children left unrestricted from physical exercise (VSD, PS, PO-VSD) had no change over the study period. However, aerobic capacity of patients with medically imposed physical restrictions (AS) and significant residual haemodynamic lesions (PO-TF, Fontan) decreased with age. In patients with AS, PO-TF and Fontan-PO the habitual level of physical activity was significantly decreased compared to controls. Conclusion Cardiovascular exercise performance in children with medically imposed restriction of intensive physical exercise (AS) or residual haemodynamic lesions (TF and Fontan-PO) declines progressively during medium-term follow up. In the other patient groups (VSD, PS, VSD-PO), exercise performance remains stable.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 63-72 
    ISSN: 0887-3585
    Keywords: enzyme ; structure ; function ; thermostability ; proteolysis ; drug resistance ; β-lactams ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The stability properties of six natural mutants of the TEM-1 β-lactamase have been studied. The glutamate to lysine substitution at positions 104 and 240 stabilize the enzyme. Conversely, the G238S mutant's decreased stability might reflect an altered conformation of the active site and thus be related to the modified substrate profile. The relative stability of the R164S and R164H mutants is explained by the formation of a hydrogen bond between these residues and Asp-179 conferring a somewhat different structure to the omega loop and thus also explaining the extended substrate profile of these mutants. The loss of stability of the R164H mutant with increasing pH values can be explained by the titration of a hydrogen bond between the Nδ of His-164 and the Oδ of Asp-179. The properties of the G238S+E104K double mutant which is the most active against third-generation cephalosporins result from a balance of destabilizing and stabilizing substitutions, and their effects seem to be additive. The behavior of the R164S + E240K mutant might be explained on the basis of a similar compensation phenomenon. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...