Find out the mystery of the mechanism of vitamin C synthesis in plants

Perhaps Vitamin C is the most important small molecule whose biological synthesis pathway remains a mystery to scientists to this day. However, a group of Dartmouth and UCLA researchers, who studied genes related to aging and cancer in animals, discovered the missing final information of this mystery. Their work is published online in the April 26 issue of Biological Chemistry .

Dr. Steven Clarke of the UCLA Molecular Biology Institute and the Department of Chemistry and Biochemistry explains that 'We have conducted experiments on a gene that is of interest in worms' . The understanding of this gene led to another understanding until 'we successfully deciphered the last enigmatic enzyme in the process of vitamin C biosynthesis in plants,' said Dr. Charles Brenner in central Vietnam. Norris Cotton Cancer Center and the genetic room of Dartmouth Medical School.

Vitamin C is an essential vitamin for humans, it is known for its antioxidant and enzyme cofactor. Humans do not have the ability to synthesize vitamin C, so they must be absorbed from the dietary foods, mainly from plants.

It was not until 1998 that a biosynthesis mechanism was proposed to explain the mechanism of vitamin C synthesis in plants . Studies from then until now have largely verified this mechanism, although the gene that takes the seventh step in a total of 10 steps to convert glucose to vitamin C is still a mystery.

The process of vitamin C biosynthesis was proposed in 1998. (Photo: saps.plantsci.cam.ac.uk)

The research process began with an attempt to find the role of a gene in C. elegans, a tiny worm used by Clarke's researcher Tara Gomez as a specimen. to study the aging process. The sequencing of the gene indicates that it is associated with a family of mutated genes in cancer, whose scientific name is HIT gene .

The collaboration between the two laboratories discovered the similarity in the gene of this worm with the product of the gene VTC2 of a wild mustard named Arabidopis thaliana, a roadside plant whose genome was know exacly. Previously, scientists found a correlation between mutations in the gene of this plant with low levels of vitamin C. Therefore, the current research process focuses on determining how how this VTC 2 gene product contributes to vitamin C synthesis.

Vitamin C is abundant in plant foods (Photo: Ecofriend.org) The team of researchers led by Dr. Brenner and Dr. Clarke recreates the seventh, an unknown step for a long time. , in the synthesis of vitamin C in the laboratory , a reaction they describe is a start-up step. They then compared the first six steps of vitamin C synthesis with a map of many glucose metabolism processes to possible cellular compounds. However, once the product of step 6 is a compound called GDP-L-galactose that can escape where VTC2 is present, the atoms will be reconfigured to target vitamin C synthesis. Especially making some other vitamins. The remaining three stages are like a winding road that needs bends but no real choice and cannot run back.

Thanks to the efforts directed by Dr. Dr. Carole Linster of UCLA whose enzyme VTC2 was expressed and purified from bacteria. After preparing galactose GDP-L-, the team demonstrated that the VTC2 gene is responsible for the seventh step, the step that researchers have been searching for long in the synthesis of vitamin C.

Because enzymes that catalyze initiating steps in the synthesis process show biological regulator positions, researchers hope this discovery could lead to new strategies for increasing the dose. The amount of vitamin C in food crops, this means there will be more nutritious foods as well as higher yields. They also need to discover how VTC2-related genes work in animals and how these genes are related to aging and cancer.

Lam Son