A systematic study of halide-template effects in the assembly of lanthanide hydroxide cluster complexes with histidine

2021 ◽  
Vol 8 (1) ◽  
pp. 26-34
Author(s):  
Weiming Huang ◽  
Zhonghao Zhang ◽  
Yinglan Wu ◽  
Wanmin Chen ◽  
David A. Rotsch ◽  
...  
Keyword(s):  
Systematic Study ◽  
Lanthanide Ions ◽  
Cluster Complexes ◽  
Hydrolysis Of ◽  
Lanthanide Hydroxide ◽  
Controlled Hydrolysis

Controlled hydrolysis of lanthanide ions in the presence of histidine and halide templates of different sizes produced dodeca- and pentadecanuclear lanthanide hydroxide clusters.

Synthesis of Submicron, Narrow Size Distribution Spherical Zincite

1986 ◽  
Vol 73 ◽  
Author(s):  
Robert H. Heistand ◽  
Yee-Ho Chia
Keyword(s):  
Size Distribution ◽  
Surface Area ◽  
Systematic Study ◽  
Spherical Particles ◽  
Narrow Size Distribution ◽  
Crystallite Sizes ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

ABSTRACTZincite has been produced by the controlled hydrolysis of an alkylzinc alkoxide (ethylzinc-t-butoxide) resulting in ∼0.2 μm spherical particles with a narrow size distribution consisting of 150 Å crystallites. The surface area is 30 m2/g. Variation of the concentration of the water drastically affects the particle and crystallite sizes. The results of a systematic study of the hydrolysis parameters are reported here.

scholarly journals Interactions of tervalent lanthanide ions with bacterial collagenase (clostridiopeptidase A)

1981 ◽  
Vol 195 (3) ◽  
pp. 677-684 ◽  
Author(s):  
Christopher H. Evans
Keyword(s):  
Ionic Radius ◽  
Substrate Inhibition ◽  
Volume Ratio ◽  
Binding Pocket ◽  
Lanthanide Ions ◽  
Ionic Radii ◽  
Apparent Dissociation Constant ◽  
Substrate Complex ◽  
Bacterial Collagenase ◽  
Hydrolysis Of

Tervalent cations of the lanthanide (rare-earth) elements reversibly inhibit bacterial collagenase (clostridiopeptidase A; EC 3.4.24.3). Sm3+, whose ionic radius is closest to that of Ca2+, is the most effective inhibitor, completely suppressing clostridiopeptidase activity at a concentration of 100μm in the presence of 5mm-Ca2+. Er3+ and Lu3+, which both have ionic radii smaller than either Ca2+ or Sm3+, inhibit less efficiently, and La3+, which is slightly larger than Ca2+ or Sm3+, inhibits only weakly. These findings indicate a closely fitting, stereospecific, Ca2+-binding pocket in clostridiopeptidase, which excludes ions that are only slightly larger than Ca2+ [ionic radius 0.099nm (0.99 Ȧ)]. By contrast, trypsin, an enzyme whose activity does not depend on Ca2+, requires lanthanide concentrations 50–100-fold greater for inhibition. Furthermore, the relative efficiency of inhibition of trypsin by lanthanides increases as the lanthanide ions become smaller and the charge/volume ratio increases. At a concentration of 50μm, Sm3+ lowers the apparent Km for the hydrolysis of Pz-peptide by clostridiopeptidase from 5.4mm to 0.37mm and the apparent Vmax. from 0.29 Wünsch–Heidrich unit to 0.018 unit. Thus Sm3+ enhances the affinity of this enzyme for its substrate; inhibition of hydrolysis of Pz-peptide may result from the excessive stability of the enzyme–Sm3+–substrate complex. Inhibition by Sm3+ is competitive with regard to Ca2+. The apparent dissociation constant, Kd, of Ca2+ is 0.27mm, where the Ki for Sm3+ is 12μm. Clostridiopeptidase is more thermolabile in the absence of Ca2+. With Sm3+, thermoinactivation of the enzyme at 53°C or 60°C is initially accelerated, but then becomes retarded as heating continues. Lanthanide ions bind to gelatin and collagen. In so doing, they appear to protect these substrates from lysis by clostridiopeptidase through mechanisms additional to supplanting Ca2+ at its binding site on the enzyme. Collagen and gelatin sequester sufficient lanthanide ions to gain partial protection from clostridiopeptidase in the absence of an extraneous source of these inhibitors.

scholarly journals Characterization of Glycoside Hydrolase Family 5 Proteins in Schizosaccharomyces pombe

2010 ◽  
Vol 9 (11) ◽  
pp. 1650-1660 ◽  
Author(s):  
Encarnación Dueñas-Santero ◽  
Ana Belén Martín-Cuadrado ◽  
Thierry Fontaine ◽  
Jean-Paul Latgé ◽  
Francisco del Rey ◽  
...  
Keyword(s):  
Cell Wall ◽  
Schizosaccharomyces Pombe ◽  
Protein Characterization ◽  
Wall Material ◽  
Glycoside Hydrolase Family ◽  
Content Type ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis ◽  
Hydrolase Family

ABSTRACT In yeast, enzymes with β-glucanase activity are thought to be necessary in morphogenetic events that require controlled hydrolysis of the cell wall. Comparison of the sequence of the Saccharomyces cerevisiae exo-β(1,3)-glucanase Exg1 with the Schizosaccharomyces pombe genome allowed the identification of three genes that were named exg1 + (locus SPBC1105.05), exg2 + (SPAC12B10.11), and exg3 + (SPBC2D10.05). The three proteins have different localizations: Exg1 is secreted to the periplasmic space, Exg2 is a membrane protein, and Exg3 is a cytoplasmic protein. Characterization of the biochemical activity of the proteins indicated that Exg1 and Exg3 are active only against β(1,6)-glucans while no activity was detected for Exg2. Interestingly, Exg1 cleaves the glucans with an endohydrolytic mode of action. exg1 + showed periodic expression during the cell cycle, with a maximum coinciding with the septation process, and its expression was dependent on the transcription factor Sep1. The Exg1 protein localizes to the septum region in a pattern that was different from that of the endo-β(1,3)-glucanase Eng1. Overexpression of Exg2 resulted in an increase in cell wall material at the poles and in the septum, but the putative catalytic activity of the protein was not required for this effect.

Systematic Study of the Interaction Between VIV Centres and Lanthanide Ions MIII in Well Defined {VIV 2MIII}{AsIIIW9O33}2 Sandwich Type Clusters: Part 1

2007 ◽  
Vol 18 (3) ◽  
pp. 711-719 ◽  
Author(s):  
Alice Merca ◽  
Achim Müller ◽  
Joris van Slageren ◽  
Mechtild Läge ◽  
Bernt Krebs
Keyword(s):  
Systematic Study ◽  
Lanthanide Ions ◽  
Sandwich Type

scholarly journals Production of Xylo-oligosaccharides (XOS) by controlled hydrolysis of Xylan using immobilized Xylanase from Aspergillus niger with improved properties

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Caio C. Aragon ◽  
Ana I. Ruiz-Matute ◽  
Nieves Corzo ◽  
Rubens Monti ◽  
Jose M. Guisán ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

Physical Chemistry of Controlled-Hydrolysis of Propanol Zirconia Doped with Yttrium Nitrite

1996 ◽  
Vol 12 (06) ◽  
pp. 547-550
Author(s):  
Peng Ding-Kun ◽  
◽  
Wan Chuan-Hao ◽  
Yang Ping-Hua ◽  
Liu Jin ◽  
...  
Keyword(s):  
Physical Chemistry ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis
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