subject: The Phytochrome Protein [print this page] The phytochrome is a protein with activity kinase present in green vegetables, whose function is to act as a photoreceptor primarily red light (600-700nm) and far-red (700-800nm), thanks to having a chromophore . Phytochrome in the type of detected light can trigger different responses in the plant, such as flowering , the germination , growth and escape response to the development of epicotyls shadow at night and during the day-cotyledons, regulation of expression metabolic activity during day and night ( circadian rhythms ).
Phytochromes were discovered in the fifties as part of an investigation into the effect of light on the germination of seeds of lettuce . It was noted that they accounted for 20% seeds germinated in darkness, by contrast, the percentage of germination was maximum when irradiated seeds with a pulse of red light (R). We found also that subsequent irradiation with far-red light pulse (RL) canceling the inductive effect of red light, preventing germination.
The alternate irradiation with light R and RL (R, R + RL R + RL + R, R + RL + R + RL, etc..) Showed that the last color applied determined the germination of seeds and light was red process stimulating factor and its inhibitor, far-red light.
In search of an explanation of such phenomena is proposed the existence of a pigment , which they called phytochrome, absorbing red light. Phytochrome in question, after absorbing red light, turned into a form capable of absorbing far-red radiation, so that rendered its initial condition after making such an absorption. Experimental support the hypothesis found in the early sixties with purification, from extracts of seedlings of cereals, a protein endowed with the predicted characteristics. The phytochromes are proteins soluble found in the seeds , leaves , stems , roots and other plant organs. 2
Biochemically, phytochrome is a protein with a chromophore Bilin .
Phytochrome has been found in most plants, including all higher plants, also very similar molecules have been found in several bacteria . A fragment of a bacterial phytochrome has clarified the structure of the protein three-dimensional.
Other plant photoreceptors include the cryptochromes and phototropins , which are sensitive to light blue and ultraviolet regions of the spectrum.
The phytoestrogens are chemical compounds nonsteroidal, found in plants but are similar to estrogens human action and similarly (oestrogenic) or opposite (antiestrogenic effect) thereto. Usually found in very small amounts in foods. Its estrogenic activity is mainly due to its chemical similarity with animal hormones. The mycoestrogens have similar effects. Its relevance to nutrition research is still in effect in areas such as the regulation of cholesterol or of maintaining the bone density at menopause. Since the ingestion of these compounds is related to a particular eating habits is difficult to distinguish the real cause of the positive effects.
These compounds are mainly flavonoids . The best known are isoflavones commonly found in soy and in red clover . The lignan phytoestrogen is also an important though not a flavonoid.
While it can be identified several ways:
isoflavones
Lignans
coumestans
and other
The most active and relevant for human consumption are the first.
The isoflavones found in a variety of plants and vegetables, especially in legumes and grasses . Two of the most abundant species in these chemicals are soy and red clover .
To exert their beneficial effect on the body, must be altered by the gut and then metabolized and processed at the liver .
