Inhibition and simulation of proteolytic enzyme activities by soil humic acids

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 253 ◽  
Author(s):  
JN Ladd ◽  
JHA Butler
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Metal Ion ◽  
Proteolytic Enzymes ◽  
Relative Effectiveness ◽  
Trypsin Activity ◽  
Carboxypeptidase A ◽  
Molecular Weights ◽  
Soil Humic Acids ◽  
Stimulation Of

The effects of neutralized solutions of soil humic acids on the activities of a range of proteolytic enzymes and of tyrosinase have been measured. Humic acids inhibit carboxypeptidase A, chymotrypsin A, pronase, and trypsin activities, stimulate papain, ficin, subtilopeptidase A, and thermolysin activities, and had no effect on phaseolain and tyrosinase activities. Stimulation of papain and ficin activities is not due to formation of metal ion-humic acid complexes. Inhibition of trypsin activity and stimulation of papain activity increased with increasing molecular weight of the humic acid. However, humic acid fractions of varying molecular weights had similar effects on the magnitude of inhibition of pronase and carboxypeptidase A activities. Polycondensates derived from p-benzoquinone and catechol influenced enzyme activity in the same way as humic acids, although the order of their relative effectiveness changed with different enzymes. Polyacrylate preparations were the most effective inhibitors of trypsin activity but had no effect on papain and ficin activities.

Biodegradation of soil humic acids by Streptomyces viridosporus

1992 ◽  
Vol 38 (3) ◽  
pp. 203-208 ◽  
Author(s):  
C. Yanze Kontchou ◽  
Roland Blondeau
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sole Source ◽  
White Rot ◽  
White Rot Fungus ◽  
Mineral Salts ◽  
Experimental Conditions ◽  
Streptomyces Viridosporus ◽  
Soil Humic Acids

Biodegradation of soil humic acids by Streptomyces viridosporus ATCC 39115 growing in a mineral salts – glucose medium was demonstrated. This biodegradation accompanies bacterial growth and is, therefore, presumed to be a primary metabolic activity, but humic acids were not used as the sole source of carbon. This bacterial activity was enhanced when cells were shaken and within a pH range of 6.5–8.5. In further experiments, the relative abilities of S. viridosporus to mineralize [14C]melanoidin, used as synthetic humic acid, were also established. In contrast to the white rot fungus Phanerochaete chrysosporium, another microorganism exhibiting humic acid degrading activity at acidic pH, poor extracellular activities were found in culture medium of S. viridosporus, and veratryl alcohol does not result in increased humic acid degradation. In spite of some peroxidase activity measured in culture filtrates and analyzed by polyacrylamide gel electrophoresis, the humic acid degrading system of S. viridosporus, in these experimental conditions, seems to be cell associated. Key words: humic acid biodegradation, melanoidin mineralization, Streptomyces viridosporus, cell-bound humic acids.

Comparison of some properties of soil humic acids and synthetic phenolic polymers incorporating amino derivaties

Soil Research ◽  
1966 ◽  
Vol 4 (1) ◽  
pp. 41 ◽  
Author(s):  
JN Ladd ◽  
JHA Butler
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
Humic Acids ◽  
Gel Filtration ◽  
Quinone Imine ◽  
Peptide Bonds ◽  
Molecular Weights ◽  
Soil Humic Acids ◽  
Properties Of Soil

Twenty-three model phenolic polymers, either nitrogen-free or incorporating amino acids, peptides, or proteins, have been prepared from p-benzoquinone and catechol under mild oxidative conditions. Two lines of experimentation have demonstrated properties of soil humic acids closely similar to those of polymers incorporating proteins, but different from those of polymers incorporating amino acids: (1) fractionation of humic acids and synthetic polymers by 'Sephadex' gel filtration showed that the percentage of components of molecular weights nominally greater than 100 000 ranged from 52-76 % for eight humic acids tested, 53-59 % for benzoquinone-protein polymers (excluding polymers containing protamine), but less than 20% for all other polymers; (2) acid hydrolysis with 6M HCl resulted in a partial release of polymer nitrogen. Amino acid nitrogen in the hydrolysates accounted for 32.4-51.9 % of humic acid nitrogen, 31.2-56.3 % of the nitrogen of polymers incorporating protein, but less than 10.8% of the nitrogen of polymers incorporating individual amino acids. Experiments with model monomeric N-phenylglycine derivatives and with polymers incorporating simple peptides showed that the bond between the carbon atom of an aromatic ring and the nitrogen atom of an a-amino acid is far more stable to acid hydrolysis than peptide bonds or bonds linking amino acids in humic acids. Glycine is, however, readily released from N-phenylglycine derivatives when conditions favour their oxidation to a quinone-imine intermediate. Incorporation of proteins into phenolic polymers prevented the detection of peptide bonds by the Folin reagent.

The Chemistry of Fungal Humic Acid-like Polymers and of Soil Humic Acids

1973 ◽  
Vol 37 (2) ◽  
pp. 229-236 ◽  
Author(s):  
M. Schnitzer ◽  
M. I. Ortiz de Serra ◽  
K. Ivarson
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Soil Humic Acids

The effect of methylation of humic acids on their influence on proteolytic enzyme activity

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 263 ◽  
Author(s):  
JHA Butler ◽  
JN Ladd
Keyword(s):  
Enzyme Activity ◽  
Humic Acid ◽  
Humic Acids ◽  
Proteolytic Enzyme ◽  
Direct Relationship ◽  
Proteolytic Enzymes ◽  
Carboxyl Groups ◽  
Proteolytic Enzyme Activity ◽  
Acid Sample

Humic acids, methylated with diazomethane, no longer inhibit or stimulate proteolytic enzymes. If an exhaustively methylated humic acid sample is hydrolysed to different degrees, there is a direct relationship between the number of carboxyl groups freed and the effect of the sample on the activities of four proteolytic enzymes. When fully hydrolysed the humic acid sample has essentially the same effect as the untreated humic acid, although the phenolic groups are still methylated. These results suggest that carboxyl groups, not phenolic groups, are responsible for the influence of humic acids on enzyme activity.

scholarly journals Humic acid complexation to Zn and Cd determined with the new electroanalytical technique AGNES

2007 ◽  
Vol 4 (5) ◽  
pp. 347 ◽  
Author(s):  
Encarnació Companys ◽  
Jaume Puy ◽  
Josep Galceran
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Metal Ion ◽  
Deposition Time ◽  
Aquatic Environments ◽  
Free Concentration ◽  
Know How ◽  
Soil Humic Acid ◽  
Free Metal

Environmental context. Humic substances are complex mixtures that play an important role in trace metal bioavailability in soils and aquatic environments. The bioavailability of a metal depends on what chemical forms, or species, it is in. We need to know how much of the metal is present as a free metal ion in solution, and how much is bound up in complexes with humic acids, for example. This work reports the complexation of Cd and Zn to humic acids by means of a simple and robust technique, AGNES (absence of gradients and Nernstian equilibrium stripping). Abstract. AGNES (absence of gradients and Nernstian equilibrium stripping), an emerging electroanalytical technique specifically designed for the determination of the free concentration of heavy metals in aqueous solutions, is here implemented to characterise the binding of CdII and ZnII to a soil humic acid. A set of metal titration experiments were performed by adding Cd or Zn to a purified humic acid (Aldrich) at pH 4, 5, 6 and 7 and measuring the free metal concentration by AGNES. The application of a program with two potential steps along the deposition stage allows for the reduction of the deposition time in the humic titration. The polyelectrolytic effects of the macromolecular ligand were taken into account through the Donnan model. Data free of electrostatic effects were reasonably described by the NICA isotherm, which accounts for heterogeneity, considering just a monomodal distribution (because of the range of pH covered). The obtained affinity parameters indicate a similar strength for Zn and Cd binding to the purified humic acid.

Interaction between uranium and humic acid (I): Adsorption behaviors of U(VI) in soil humic acids

2007 ◽  
Vol 18 (5) ◽  
pp. 287-293 ◽  
Author(s):  
M WEI ◽  
J LIAO ◽  
N LIU ◽  
D ZHANG ◽  
H KANG ◽  
...  
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Adsorption Behaviors ◽  
Soil Humic Acids

Release of amino acids from soil humic acids by proteolytic enzymes

Soil Research ◽  
1967 ◽  
Vol 5 (2) ◽  
pp. 161 ◽  
Author(s):  
JN Ladd ◽  
PG Brisbane
Keyword(s):  
Amino Acids ◽  
Acid Hydrolysis ◽  
Humic Acids ◽  
Direct Evidence ◽  
Proteolytic Enzymes ◽  
Approximate Inverse ◽  
Peptide Bonds ◽  
Aromatic Content ◽  
Phenolic Polymer ◽  
Soil Humic Acids

Direct evidence for the occurrence of peptide bonds in soil humic acids has been obtained by showing that the proteolytic enzyme pronase releases a-amino acids from each of 10 humic acids. The maximal amounts of amino acids liberated by pronase accounted for 27.6-39.4% of those released by hot acid hydrolysis. The susceptibility of humic acids to proteolytic attack showed an approximate inverse relationship with their aromatic content, based on their absorbance at 260 or 450 m�. Both pronase and papain attacked casein less readily when it was incorporated into a phenolic polymer prepared from p-benzoquinone. Papain was inactive towards soil humic acids. Similar amino acids were released by pronase from each of five humic acids tested. The amino acid patterns showed no basic amino acids but relatively high proportions of leucine (isoleucine) as compared with those obtained by acid hydrolysis. The action of pronase on humic acids had little effect on the molecular weight distribution of the humic components.

Sign in / Sign up

Export Citation Format

Share Document