similar to that of Grossbard and Schimke (2).
Protein estimations were carried out using the Lowry method.

The solubilisation of precipitable enzyme activity was studied
using the washed 100,000 g. precipitate, suspended in SPG by sonica-
tion. This material was treated in various ways, incubated for about
? hour, its HK activity measured, and the suspension spun at 100,000
g. for 60 mins. The HK activity in the supernatant was measured.

All manipulations were performed in the cold.

RESULTS AND DISCUSSION. The results are presented in Table 1. It
will be noted that the total amounts of enzyme in the sperm of each
species are, within a factor of 3, the same, and that the distribu-
tion pattern is similar. Attention is also drawn to the considerable
quantities of hexokinase activity present extracellularly in ram and
bull semen, and to the lack of it in boar semen; the differences are
more than can be accounted for on a sperm density relationship, but
may have a partial explanation in the relative fragility of the kino-
plasmic droplets compared between the three species.

It was the purpose of this experiment to see whether the quanti-
ties of HK (suggested, with phosphofructokinase, as a possible
control enzyme of glycolysis (3, 4) reflected the fructolytic pro-
perties of the species; it is assumed that fructose is metabolised
by the same route as glucose (5). Mann (1) has given the fructolysis
index of ram and bull sperm as about 1.7 mg/hr/lO9 cells at 37°, and
that of boar sperm as only 05345. These figures correspond to 0.153
MM and 0.032 uM used /min/107 cells at 37°. Assuming that the enzyme
will utilise fructose at least 1.4 times as quickly as glucose (un-
published results, but see (5)), then there is enough enzyme to
utilise under maximal conditions 3.4 sM/min/109 cells in the bull,
280 /.M/min/lo9 cells in the ram, and 1.2}«M/min/109 cells in the boar.
Thus a large excess of enzyme is present, and the slightly lower
enzyme activity in boar sperm is not sufficient to account for its
much lower fructolysis index.

Various treatments have been used to solubilise particulate
hexokinase, notably salt concentration, detergents, and substrates

(2) L. GROSSBARD & R. T. SCHIMKE, 1966. J. Biol. Chem., 2413 3546.
(3) 0. H. LOWRY & J. V. PASSONNEAU, 1964. J. Biol. Chem., 239: 31.
(4) K. UYEDA & E. RACKER, 1965. J. Biol. Chem., 240: 4682, 4689.

(5) R. RIKMENSPOEL & R. CAPUTO, 1966. J. Reprod. Fertil., 12: 437.

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