VITELLINE MEMBRANE AND CORTICAL PARTICLES 285
of the peripheral region of the egg, whereas the consistency of the endoplasm was not influenced. These results were in keeping with the view
that mucopolysaccharides present in the cortex act as enzyme inhibitors
which are removed when the egg is activated.
The removal of an added inhibitor by the addition of NaI0 4 is due to
an effect on the egg surface and not on the inhibitor. Heparin or
Felnh(Fu) are in themselves not sensitive to periodate in the low concentration and the brief duration of treatment that were used in the
fertilization experiment referred to above (Esping, 1957b). There must
be an additive effect of the "natural" and the added inhibitor. When
the first one is reduced by periodate, the latter demonstrates its own
effect. The periodate sensitivity of the egg surface indicates that the
target substances in the egg must possess easily available α-glycol
groups. This is the case with the jelly coat substance, the viscosity of
which decreases rather rapidly upon treatment with 5-10 Χ 10~
5 M
NaI0 4 . This must not necessarily mean that a profound splitting occurs;
even a relatively mild depolymerization of the substance may give this
result. The same may apply to the periodate-sensitive compounds in the
egg surface. The enzyme inhibitory effect may be removed by some few
steps of depolymerization.
The evidence presented in this section indicates that the assumption of
heparin-like enzyme inhibitors in the surface of the mature unfertilized
egg may still be of value as a working hypothesis which has to be tested
further in experimental work.
An investigation on the interaction of fibrinogen with dextran sulfate
by Sasaki and Nogucki (1959) is of great interest as a model related to
the problems under discussion in this section. Under certain conditions
the two compounds form an insoluble complex. The precipitation is dependent on the weight ratios between the dextran sulfate and the
fibrinogen rather than on absolute concentrations. An increased degree of
esterification of the dextran sulfate increases the precipitation at a constant weight ratio. The precipitation becomes progressively more inhibited at higher pH value. An increase of the salt concentration and an
increase in temperature to 35-45°C had the same effect. On the other
hand, increasing the molecular weight of the dextran sulfate increased
the precipitation.
The sulfate group plays evidently a great role in the binding of the
protein because dextran without sulfate or sodium carboxymethylcellulose that has carboxyl groups do not bind fibrinogen. The bonds
between dextran sulfate and fibrinogen are weak bonds, and they presumably represent hydrogen bonds in which the sulfate groups participate. The authors point out that S0 3 " groups have a stronger tendency
of the peripheral region of the egg, whereas the consistency of the endoplasm was not influenced. These results were in keeping with the view
that mucopolysaccharides present in the cortex act as enzyme inhibitors
which are removed when the egg is activated.
The removal of an added inhibitor by the addition of NaI0 4 is due to
an effect on the egg surface and not on the inhibitor. Heparin or
Felnh(Fu) are in themselves not sensitive to periodate in the low concentration and the brief duration of treatment that were used in the
fertilization experiment referred to above (Esping, 1957b). There must
be an additive effect of the "natural" and the added inhibitor. When
the first one is reduced by periodate, the latter demonstrates its own
effect. The periodate sensitivity of the egg surface indicates that the
target substances in the egg must possess easily available α-glycol
groups. This is the case with the jelly coat substance, the viscosity of
which decreases rather rapidly upon treatment with 5-10 Χ 10~
5 M
NaI0 4 . This must not necessarily mean that a profound splitting occurs;
even a relatively mild depolymerization of the substance may give this
result. The same may apply to the periodate-sensitive compounds in the
egg surface. The enzyme inhibitory effect may be removed by some few
steps of depolymerization.
The evidence presented in this section indicates that the assumption of
heparin-like enzyme inhibitors in the surface of the mature unfertilized
egg may still be of value as a working hypothesis which has to be tested
further in experimental work.
An investigation on the interaction of fibrinogen with dextran sulfate
by Sasaki and Nogucki (1959) is of great interest as a model related to
the problems under discussion in this section. Under certain conditions
the two compounds form an insoluble complex. The precipitation is dependent on the weight ratios between the dextran sulfate and the
fibrinogen rather than on absolute concentrations. An increased degree of
esterification of the dextran sulfate increases the precipitation at a constant weight ratio. The precipitation becomes progressively more inhibited at higher pH value. An increase of the salt concentration and an
increase in temperature to 35-45°C had the same effect. On the other
hand, increasing the molecular weight of the dextran sulfate increased
the precipitation.
The sulfate group plays evidently a great role in the binding of the
protein because dextran without sulfate or sodium carboxymethylcellulose that has carboxyl groups do not bind fibrinogen. The bonds
between dextran sulfate and fibrinogen are weak bonds, and they presumably represent hydrogen bonds in which the sulfate groups participate. The authors point out that S0 3 " groups have a stronger tendency