Human proteins

Bioengineered crops seem to be a cheap way of producing proteins and enzymes

Published: Monday 15 September 1997

a genetically engineered rice that can produce human proteins and can be harvested just like any other crop, has been developed by California-based Applied Phytologics. This technique could make it cheaper to produce many bioengineered proteins such as those found in detergents ( New Scientist , Vol 155, No 2090).

The most common way of manufacturing bioengineered proteins is by brewing them with the genetically engineered microorganism in a bioreactor. Some researchers have begun experimenting with plants, often leafy crops such as tobacco. But Applied Phytologics is the first company that is using a cereal, says Roger Beachy, head of plant biology at the Scripps Research Institute in La Jolla, California, and a scientific adviser to the company.

"I think it is going to dawn on the industry shortly that in plant biotechnology, cereal grains are going to be the crop to work with," says Raymond Rodriquez, chairperson of Applied Phytologics.

In March this year, the company planted 4,200 rice plants engineered to manufacture alpha-1-antitrypsin, a human protein that could be used to treat liver disease and haemorrhage. The rice will be harvested this month and the protein extracted by malting, in which the grain is allowed to germinate. The idea, says Rodriquez, is to use existing agricultural techniques on a mass scale to make products at low cost.

In normal malting, the seed produces an enzyme that begins to turn the starch in the seed into sugar. The company has engineered the seed so that, instead of expressing the normal enzyme, it expresses the required protein. Later the protein can be extracted from the malted grain.

Rodriquez says his company will concentrate on products for which there is great demand, such as enzymes for washing powder or proteins used to stop blood products clotting. The demand for these products will make it economical to produce hundreds of tonnes at a time.

Rodriquez expects to produce commercial quantities of non-medical products within four years, and to have regulatory approval for some of the medical products within seven years.

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