8. POLYSACCHARIDASES
413
purified, and obtained in the crystalline form (345) before the chemical
nature of its substrate was known. The bacteriolytic action of lysozyme
on certain microorganisms, in particular Micrococcus lysodeikticus and
Sarcina lutea was for some time the only known activity of this enzyme.
In 1946, Meyer and Hahnel (346) fractionated the cell material of
Micrococcus lysodeikticus and of certain other microorganisms and
obtained a highly polymerized phosphomucopolysaccharide (J), containing 5.5-6.5% nitrogen and 23-30% hexosamine. This material was
found to be a suitable substrate for lysozyme. The enzyme was able to
reduce the high viscosity of the substrate solutions in an initial reaction
and to produce reducing substances during the later stages.
Considerable similarities exist between the modes of action of
lysozyme and hyaluronidase. Both enzymes catalyze the depolymerization of their respective substrates, first producing a marked decrease in
the viscosity and later an increase in the reducing power. Both enzymes
can be reversibly oxidized.
Lysozyme was originally found in nasal mucus and in egg white,
from which latter source it has been obtained in the crystalline form.
The occurrence of lysozyme in the latex of different plants, i.e., Ficus
and Papaya, has been demonstrated, and the enzymes of plant and
animal origin have been compared (347). Ficus lysozyme is different
from the egg white enzyme in its pH optimum of action, its stability,
electrophoretic behavior, ability to be adsorbed on bentonite, and behavior toward some strains of Micrococcus lysodeikticus and Sarcina.
Lysozyme also occurs in microbes, in particular in those susceptible to
the enzyme (348). The physiological role of lysozyme has been discussed
by Meyer (346), who believes that its function appears to be primarily
metabolic, concerned mainly with the depolymerization and breakdown
of its substrate. In this case, as Meyer pointed out, one would have to
anticipate a wide occurrence of its substrate which, so far, could not be
observed. The role of lysozyme as a bacteriolytic agent, i.e., its role as a
defense mechanism, might be incidental.
XII. General Discussion
The principal function of the large majority of polysaccharidases
appears to consist in their ability to transform high molecular and, in
many instances, totally insoluble, substrates into water-soluble, low
molecular substances. Unlike polysaccharides, the products of polysaccharidase action are capable of penetrating into the cells where they may
subsequently undergo further metabolic changes. Consequently, most of
the polysaccharidases, whether they occur in animals, higher plants, or
microorganisms, are extracellular enzymes. This is particularly true for
413
purified, and obtained in the crystalline form (345) before the chemical
nature of its substrate was known. The bacteriolytic action of lysozyme
on certain microorganisms, in particular Micrococcus lysodeikticus and
Sarcina lutea was for some time the only known activity of this enzyme.
In 1946, Meyer and Hahnel (346) fractionated the cell material of
Micrococcus lysodeikticus and of certain other microorganisms and
obtained a highly polymerized phosphomucopolysaccharide (J), containing 5.5-6.5% nitrogen and 23-30% hexosamine. This material was
found to be a suitable substrate for lysozyme. The enzyme was able to
reduce the high viscosity of the substrate solutions in an initial reaction
and to produce reducing substances during the later stages.
Considerable similarities exist between the modes of action of
lysozyme and hyaluronidase. Both enzymes catalyze the depolymerization of their respective substrates, first producing a marked decrease in
the viscosity and later an increase in the reducing power. Both enzymes
can be reversibly oxidized.
Lysozyme was originally found in nasal mucus and in egg white,
from which latter source it has been obtained in the crystalline form.
The occurrence of lysozyme in the latex of different plants, i.e., Ficus
and Papaya, has been demonstrated, and the enzymes of plant and
animal origin have been compared (347). Ficus lysozyme is different
from the egg white enzyme in its pH optimum of action, its stability,
electrophoretic behavior, ability to be adsorbed on bentonite, and behavior toward some strains of Micrococcus lysodeikticus and Sarcina.
Lysozyme also occurs in microbes, in particular in those susceptible to
the enzyme (348). The physiological role of lysozyme has been discussed
by Meyer (346), who believes that its function appears to be primarily
metabolic, concerned mainly with the depolymerization and breakdown
of its substrate. In this case, as Meyer pointed out, one would have to
anticipate a wide occurrence of its substrate which, so far, could not be
observed. The role of lysozyme as a bacteriolytic agent, i.e., its role as a
defense mechanism, might be incidental.
XII. General Discussion
The principal function of the large majority of polysaccharidases
appears to consist in their ability to transform high molecular and, in
many instances, totally insoluble, substrates into water-soluble, low
molecular substances. Unlike polysaccharides, the products of polysaccharidase action are capable of penetrating into the cells where they may
subsequently undergo further metabolic changes. Consequently, most of
the polysaccharidases, whether they occur in animals, higher plants, or
microorganisms, are extracellular enzymes. This is particularly true for