Content of silicon in fractions of plant protein

Silicon is biologically important element that is necessary not only for plant, but for all living organisms. Silicon was discovered in all plant organs, where its much quantity accumulates in plan cell walls of leaf and root, giving them a mechanical durability and resistance against abiotic and biotic stresses. Earlier, it was supposed that the silicon was absorbed by plants in form of monosilicic acid and then being deposited as phytoliths or accumulated in epidermal plant cells. Moreover the silicon is not only a basic structural element, but it controls many biological and chemical processes. Water soluble monosilicic acid enters into reaction with metals, organic compounds, showing properties of weak acid. Gels of silicic acid can be a catalyst and a matrix, on which the inner cellular synthesis of organic compounds occurs. In the present study the method to determinate three forms of silicon in plants, such as free, easily hydrolyzed and tightly combined is given. Thus, the part of silicon, 0.5-0.7% was observed in protein preparation of leaves of amaranth. Protein was divided into two fractions, albumins and globulins by precipitation with ammonium sulfate. After that each protein fraction was divided into two by Sephadex, where one of which come out in inner volume of gel, and second one come out in outer volume of gel (G-75). The gel distribution into fractions was of the same type characteristics. The tightly combined silicon was absent in high molecular fraction of albumins and globulins. Most of the silicon was discovered in high molecular fraction of globulins, where 80% of the element was represented by an easily hydrolyzed form. The silicon combined with proteins apparently is in a form of orthosilicic ester of hydroxy-amino acids; however it cannot be excluded that there is the formation of Si-N bonds with free amino groups. Biophile silicon is a part of plant silicon (organogenic), which is basically in the form of orthosilicic esters bonded with proteins, phospholipids and pectins that are the plant components being assimilated primarily by human’s organism. In our opinion, this fraction of silicon as a microelement should be taken into account in evaluation of nutritional, forage and pharmaceutical values of plant raw material.