Safe birth control 'pill' for men a step closer

Scientists, including one of Indian-origin, have discovered a way to produce a key enzyme found only in sperm, an advance that may help develop a birth control drug for men that is free of side-effects.
"The milestone reached is the production and isolation of a full-length, active kinase enzyme in sufficient quantities to conduct drug screens," said cell biologist John C Herr of the University of Virginia.
"Isolation of an active, full-length form of this enzyme allows us to test drugs that bind to the entire surface of the enzyme so that we can identify inhibitors that may exert a selective action on sperm," said Herr.

Researchers have managed to isolate and manufacture an enzyme that is found exclusively in the testes. The enzyme is found only in spermatids, cells which give rise to sperm.
By targeting this enzyme, the researchers hope to inhibit its function as sperm are made, thus decreasing the sperm's ability to swim, so that fertilisation cannot occur.
The team first had to identify an enzyme that was unique just to the testes, and to the very last step of sperm production.

"The challenge in developing a new contraceptive is that a male 'pill' will be taken by perfectly healthy men," said Herr.

"Because of this fact, a male contraceptive drug should be very precise in its mechanism of action, without any off-target side-effects on molecules with similar properties located in other organs," he said.
"By expressing an active, full-length enzyme, it positions the programme to screen for drugs that uniquely target 'pockets' in only the sperm-specific form of this enzyme, allowing for screening methods to identify drugs that selectively target sperm," Herr said.
While there are several drugs that target kinases to battle diseases such as leukemia, this would be the first time the approach has been used to create a form of birth control, said research scientist Jagathpala Shetty.

"So far there are no kinase drugs in use in contraceptive research, so this will be one of the first efforts to identify a drug inhibiting testes-specific kinase function," Shetty said.
The research was published in the journal Protein Expression and Purification.