On the role of higher plant and microbial lipases in the ruminal hydrolysis of grass lipids

1977 ◽  
Vol 38 (2) ◽  
pp. 225-232 ◽  
Author(s):  
R. M. C. Dawson ◽  
N. Hemington ◽  
G. P. Hazlewood
Keyword(s):  
Rumen Fluid ◽  
Higher Plant ◽  
Microbial Enzymes ◽  
Heat Treated ◽  
Ruminal Degradation ◽  
Complex Lipids ◽  
Microbial Lipases ◽  
Micro Organisms ◽  
Hydrolysis Of

1. The galactolipids of heat-treated, 14C-labelled rye grass S24 administered intraruminally to a sheep fed on an autoclaved diet were rapidly catabolized.2. When grass was homogenized with rumen contents devoid of higher plant lipases the grass galactolipids were rapidly metabolized, but were not metabolized when the rumen contents were boiled to destroy microbial galactolipases.3. 14C-labelled monogalactosyldiglyceride, digalactosyldiglyceride and triolein were metabolized, with the release of 14C-labelled fatty acids when incubated with a homogenate (100 g/l) of grass or clover in rumen fluid from a starved sheep, but not when the rumen fluid was heat-treated to destroy microbial enzymes.4. It is concluded that in the sheep the lipases of rumen micro-organisms play a major part in the ruminal degradation of ingested complex lipids of pasture.

scholarly journals Hydrolysis of14C-labelled proteins by rumen micro-organisms and by proteolytic enzymes prepared from rumen bacteria

1983 ◽  
Vol 50 (2) ◽  
pp. 345-355 ◽  
Author(s):  
R. J. Wallace
Keyword(s):  
Proteolytic Enzymes ◽  
Rumen Fluid ◽  
Performic Acid ◽  
Cross Linking ◽  
Acid Oxidation ◽  
Rumen Bacteria ◽  
Rate Of Hydrolysis ◽  
Micro Organisms ◽  
Hydrolysis Of

1. Proteins were labelled with14C in a limited reductive methylation using [14C]formaldehyde and sodium borohydride.2. The rate of hydrolysis of purified proteins was little (< 10%) affected by methylation and the14C-labelled digestion products were not incorporated into microbial protein during a 5 h incubation with rumen fluid in vitro. It was therefore concluded that proteins labelled with14C in this way are valid substrates for study with rumen micro-organisms.3. The patterns of digestion of14C-labelled fish meal, linseed meal and groundnut-protein meal by rumen micro-organisms in vitro were similar to those found in vivo.4. The rates of hydrolysis of a number of14C-labelled proteins, including glycoprotein II and lectin from kidney beans (Phaseolus vulgaris), were determined with mixed rumen micro-organisms and with proteases extracted from rumen bacteria. Different soluble proteins were digested at quite different rates, with casein being most readily hydrolysed.5. Proteins modified by performic acid oxidation, by cross-linking using 1,6-di-iso-cyanatohexane or by diazotization were labelled with14C. Performic acid treatment generally increased the susceptibility of proteins to digestion, so that the rates of hydrolysis of performic acid-treated proteins were more comparable than those of the unmodified proteins. Cross-linking resulted in a decreased rate of hydrolysis except with the insoluble proteins, hide powder azure and elastin congo red. Diazotization had little effect on the rate of hydrolysis of lactoglobulin and albumin, but inhibited casein hydrolysis and stimulated the breakdown of γ-globulin.

A comparison of methods for determining the concentration of extracellular peptides in rumen fluid of sheep

1990 ◽  
Vol 114 (1) ◽  
pp. 101-105 ◽  
Author(s):  
R. J. Wallace ◽  
N. McKain
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Analysis ◽  
Rumen Fluid ◽  
Amino Acid Content ◽  
Reliable Estimate ◽  
Precipitate Protein ◽  
Micro Organisms ◽  
Hydrolysis Of ◽  
Amino Acid Concentrations

SUMMARYSamples of rumen fluid were removed from pairs of sheep on four grass-hay-based diets 7 h after feeding. Micro-organisms were sedimented by centrifugation and the cell-free supernatant was treated with perchloric acid (PCA) to precipitate protein. The remaining fluid was analysed for peptides by several methods to determine how much peptide escaped degradation. Ammonia interfered with analysis by amino group reagents, especially ninhydrin. In this respect,o-phthalaldehyde and trinitrobenzene sulphonic acid were more specific and more useful than ninhydrin. Use of all these reagents showed that significant quantities of amino groups (equivalent to up to 153 mg amino acid N/1 of rumen fluid) were released by hydrolysis of the PCA extract with 6 M-HCI for 24 h. However, fluorescamine analysis indicated that the peptide content of the unhydrolysed PCA extract was < 3 mg N/1. The true amino acid content of different extracts was resolved by chromatographic amino acid analysis: the sum of individual amino acid concentrations in acid-hydrolysed PCA extracts of extracellular rumen fluid ranged from 7·8 to 14·5 mg N/1. Thus most of the free amino N released by hydrolysis of the PCA extract was not from amino acids, and most of the amino acids that were released were originally present in a form that did not react with fluorescamine. Although none of the methods gave a reliable estimate of peptide concentrations, amino acid analysis provided an upper limit. It was therefore concluded that peptide concentrations in extracellular rumen fluid are much lower than indicated by previous ninhydrin estimations, and that little dietary peptide escapes degradation for a prolonged period in the rumen.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

The role of intracanal medicaments in inhibition of bacteria isolated from root canals of infected primary molars

2019 ◽  
Vol 14 (1) ◽  
pp. 92
Author(s):  
Dr. Maha Abdul- Kareem Mahmood ◽  
Dr. Huda Elias Ali ◽  
Dr. Haraa Khairi Abdul-Kadher
Keyword(s):  
Antimicrobial Activity ◽  
Streptococcus Mutans ◽  
Normal Saline ◽  
Root Canal ◽  
Primary Teeth ◽  
Primary Molars ◽  
Root Canals ◽  
Etiologic Agents ◽  
Micro Organisms

Microbes are considered as the primary etiologic agents in endodontic diseases.Disinfection of the root canal is obtained by the combined effect of biomechanicalpreparation, irrigation and intra canal medicament. The aim of the present study wasto assess the antimicrobial activity of intracanal medicaments (formocresol andEndosepton) against two micro organisms (Streptococcus mutans and staphylococcusaureus) isolated from 15 necrotic pulps of primary molars indicated for pulpectomyprocedure. The samples were cultured, and purified using microbiological evaluation.Broth dilution test was performed in our study by preparing test tubes containing10 ml of BHI broth (pH. 7) which then inoculated with strains of the tested bacteriaand incubated at 37 C° for 24 h. After over night incubaction, ten fold dilution weremade in test tubes containing 9 ml of normal saline by adding 1 ml of the inoculum tothe first tube . Then from dilution 10-1 , 0.1 ml of cell suspension was added to 9.9 mlof formocresol and endosepton, then 0.1 ml was taken and spread on duplicates ofBHI agar plates at different intervals and incubated aerobically for 24 h. at 37 C°.Colonies on the plates were counted after incubation and CFU/mL (colony formingunit) was calculated. Our results indicating that there were no significant differencesbetween the intracanal medicaments, but there were high significant differencesbetween the intervals time of the study. We concluded that both materials had greatantibacterial effect against the pathogens commonly isolated from necrotic pulpaltissue of primary teeth.

scholarly journals Steroid Sulphatase and Its Inhibitors: Past, Present and Future

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2852
Author(s):  
Paul A. Foster
Keyword(s):  
Good Evidence ◽  
The Past ◽  
Steroid Sulphatase ◽  
University Of Oxford ◽  
Therapeutic Value ◽  
Breast And Prostate Cancer ◽  
The University ◽  
Further Development ◽  
Hydrolysis Of

Steroid sulphatase (STS), involved in the hydrolysis of steroid sulphates, plays an important role in the formation of both active oestrogens and androgens. Since these steroids significantly impact the proliferation of both oestrogen- and androgen-dependent cancers, many research groups over the past 30 years have designed and developed STS inhibitors. One of the main contributors to this field has been Prof. Barry Potter, previously at the University of Bath and now at the University of Oxford. Upon Prof. Potter’s imminent retirement, this review takes a look back at the work on STS inhibitors and their contribution to our understanding of sulphate biology and as potential therapeutic agents in hormone-dependent disease. A number of potent STS inhibitors have now been developed, one of which, Irosustat (STX64, 667Coumate, BN83495), remains the only one to have completed phase I/II clinical trials against numerous indications (breast, prostate, endometrial). These studies have provided new insights into the origins of androgens and oestrogens in women and men. In addition to the therapeutic role of STS inhibition in breast and prostate cancer, there is now good evidence to suggest they may also provide benefits in patients with colorectal and ovarian cancer, and in treating endometriosis. To explore the potential of STS inhibitors further, a number of second- and third-generation inhibitors have been developed, together with single molecules that possess aromatase–STS inhibitory properties. The further development of potent STS inhibitors will allow their potential therapeutic value to be explored in a variety of hormone-dependent cancers and possibly other non-oncological conditions.

scholarly journals THE ENZYMATIC HYDROLYSIS OF RAW AND HEAT-TREATED EGG WHITE

1935 ◽  
Vol 109 (1) ◽  
pp. 169-175
Author(s):  
Essie White Cohn ◽  
Abraham White
Keyword(s):  
Enzymatic Hydrolysis ◽  
Egg White ◽  
Heat Treated ◽  
Hydrolysis Of

scholarly journals Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of Mg2+.

1983 ◽  
Vol 258 (22) ◽  
pp. 13673-13679 ◽  
Author(s):  
A Gómez-Puyou ◽  
G Ayala ◽  
U Muller ◽  
M Tuena de Gómez-Puyou
Keyword(s):  
Mitochondrial Atpase ◽  
Hydrolysis Of

The role of pretreatment in improving the enzymatic hydrolysis of lignocellulosic materials

2016 ◽  
Vol 199 ◽  
pp. 49-58 ◽  
Author(s):  
Shaoni Sun ◽  
Shaolong Sun ◽  
Xuefei Cao ◽  
Runcang Sun
Keyword(s):  
Enzymatic Hydrolysis ◽  
Lignocellulosic Materials ◽  
Hydrolysis Of

scholarly journals “Newton’s cradle” proton relay with amide–imidic acid tautomerization in inverting cellulase visualized by neutron crystallography

2015 ◽  
Vol 1 (7) ◽  
pp. e1500263 ◽  
Author(s):  
Akihiko Nakamura ◽  
Takuya Ishida ◽  
Katsuhiro Kusaka ◽  
Taro Yamada ◽  
Shinya Fushinobu ◽  
...  
Keyword(s):  
Glycoside Hydrolases ◽  
Side Chain ◽  
Enzymatic Reactions ◽  
X Ray Diffraction ◽  
Peptide Bonds ◽  
Proton Relay ◽  
Newton’S Cradle ◽  
Dynamics Simulations ◽  
Hydrolysis Of

Hydrolysis of carbohydrates is a major bioreaction in nature, catalyzed by glycoside hydrolases (GHs). We used neutron diffraction and high-resolution x-ray diffraction analyses to investigate the hydrogen bond network in inverting cellulase PcCel45A, which is an endoglucanase belonging to subfamily C of GH family 45, isolated from the basidiomycete Phanerochaete chrysosporium. Examination of the enzyme and enzyme-ligand structures indicates a key role of multiple tautomerizations of asparagine residues and peptide bonds, which are finally connected to the other catalytic residue via typical side-chain hydrogen bonds, in forming the “Newton’s cradle”–like proton relay pathway of the catalytic cycle. Amide–imidic acid tautomerization of asparagine has not been taken into account in recent molecular dynamics simulations of not only cellulases but also general enzyme catalysis, and it may be necessary to reconsider our interpretation of many enzymatic reactions.

Sign in / Sign up

Export Citation Format

Share Document