410
PETER BERNFELD
B. HYALURONIDASE
1. Mechanism of Action
There are considerable analogies between the actions of a-amylase
and hyaluronidase. In both cases, the initial degradation produces a
rapid decrease in the viscosity of the substrates, which, in the case of
hyaluronidase, is accompanied also by a decrease in the capability of
the substrate to be precipitated by proteins. Although the reducing
power of the substrate increases only very slightly during this first
stage of α-amylase and hyaluronidase actions, prolonged enzymatic
digestion produces reducing sugars in both enzymatic reactions. The
end products are oligosaccharides in both cases, the nature and degree
of polymerization of which depend on the source of the enzyme. Thus,
the products of exhaustive action of barley malt α-amylase on amylopectin are known to be of higher molecular weight than the end products
of salivary «-amylase digestion (39). In analogy, testicular and snake
venom hyaluronidases, splitting endohexosaminidic bonds of the substrate, yield mainly tetrasaccharide, with disaccharide appearing only as
a minor component (323), whereas hyaluronidase from microorganisms,
splitting the same bond, yields a Δ
45 (glucuronide) unsaturated disaccharide (324), whereby the unsaturation was introduced during the
enzymatic digestion. In addition, hyaluronidase of the leech (Hirudo
medicinalis) is of a different type since it hydrolyzes endoglucuronidic
bonds; it yields a tetrasaccharide like the testicular enzyme, with the
exception, however, that the latter has a hexosamine at the reducing end
group while the former has a uronic acid (325).
The action of hyaluronidase on capillary permeability was first
reported by Duran-Reynals (326); the activity to increase capillary
permeability is known as spreading factor and has been identified with
the enzymatic activity of hyaluronidase (327). This physiological phenomenon has no precedents with other polysaccharidases.
2. Occurrence
The main source of mammalian hyaluronidase is found in testicles;
bee and snake venoms (328) and leech heads (329) have also been
reported to contain hyaluronidase activity. Reports on the presence of
hyaluronidase in other mammalian tissues, such as spleen, ciliary body
and iris (330), cornea and skin (331), have been attributed to bacterial
contamination (328, 332). Salivary hyaluronidase (65) is decreased
upon penicillin administration; it is probably a bacterial enzyme (333).
No hyaluronidase activity has been reported in higher plants, but the
PETER BERNFELD
B. HYALURONIDASE
1. Mechanism of Action
There are considerable analogies between the actions of a-amylase
and hyaluronidase. In both cases, the initial degradation produces a
rapid decrease in the viscosity of the substrates, which, in the case of
hyaluronidase, is accompanied also by a decrease in the capability of
the substrate to be precipitated by proteins. Although the reducing
power of the substrate increases only very slightly during this first
stage of α-amylase and hyaluronidase actions, prolonged enzymatic
digestion produces reducing sugars in both enzymatic reactions. The
end products are oligosaccharides in both cases, the nature and degree
of polymerization of which depend on the source of the enzyme. Thus,
the products of exhaustive action of barley malt α-amylase on amylopectin are known to be of higher molecular weight than the end products
of salivary «-amylase digestion (39). In analogy, testicular and snake
venom hyaluronidases, splitting endohexosaminidic bonds of the substrate, yield mainly tetrasaccharide, with disaccharide appearing only as
a minor component (323), whereas hyaluronidase from microorganisms,
splitting the same bond, yields a Δ
45 (glucuronide) unsaturated disaccharide (324), whereby the unsaturation was introduced during the
enzymatic digestion. In addition, hyaluronidase of the leech (Hirudo
medicinalis) is of a different type since it hydrolyzes endoglucuronidic
bonds; it yields a tetrasaccharide like the testicular enzyme, with the
exception, however, that the latter has a hexosamine at the reducing end
group while the former has a uronic acid (325).
The action of hyaluronidase on capillary permeability was first
reported by Duran-Reynals (326); the activity to increase capillary
permeability is known as spreading factor and has been identified with
the enzymatic activity of hyaluronidase (327). This physiological phenomenon has no precedents with other polysaccharidases.
2. Occurrence
The main source of mammalian hyaluronidase is found in testicles;
bee and snake venoms (328) and leech heads (329) have also been
reported to contain hyaluronidase activity. Reports on the presence of
hyaluronidase in other mammalian tissues, such as spleen, ciliary body
and iris (330), cornea and skin (331), have been attributed to bacterial
contamination (328, 332). Salivary hyaluronidase (65) is decreased
upon penicillin administration; it is probably a bacterial enzyme (333).
No hyaluronidase activity has been reported in higher plants, but the