Life is made up from biomolecules with one-handed structure. L-dominant exclusive choice of enantiomeric type in optical amino acid isomers raises important issues concerning life science. This report discusses why it is essential for life to be made up of homochiral molecule. A mechanism that selects homochiral molecules lies in enzyme stereoselectivity, and therefore the studying of it will be important to solve a problem on origin of life and an enigma of life’s birth. This report concludes there is no life without homochirality.

  In general, enzymes are essential molecules for maintaining of life and are composed of various amino acids. The amino acids synthesized chemically contain both D- and L-amino acids, but enzymes contain exclusively L-amino acids in their peptide chains. This fact leed to the origin of life, and many theories were mentioned but anyway both D- and L- amino acids co-existed at the beginning of the forming of the earth. Accordingly, D-amino acids exist more than 50 milion years ago in nature, but the existence of D-amino acids have been ignored until the analytical methods for D-amino acids develope. Recently, much attention has been payed for the relationship between D-amino acid in food and their function in life.

  In this work, I will describe D-amino acid in food, especially in sake, and discuss about occurrence, production mechanism, and function of D-amino acid in sake. I analyzed D- and L-amino acids contents of 141 kind of sake by combination of 3 diffenrent chiral derivertization methods for high-performance liquid chromatography. I analyzed the relationship betwee D- or L-amino acid content and taste of sake using principle component analysis. I found that D-amino acid content of sake increased when it was produced with Kimoto. The lactic acid bacteria contained Kimoto produced extracellularly D-alanine, D-aspartic acid, and D-glutamic acid. Principle component analysis revealed that D-alanine, D-aspartic acid, and D-glutamic acid in sake increased umami and total evaluation of sake. This new function of D-amino acid in food will make various functional foods and contribute to human health in daily life.

  The protein contains D-beta-Asp (D-β-Asp protein) on palatine tonsils, nasal mucosa and vocal cords was investigated. The lymphoid follicles were mainly stained with an anti-D-β-Asp antibody increased with age in case of palatine tonsils. New finding of the existence of the D-β-Asp protein which spread around from the center to periphery was shown in the lymphoid follicles of the palatine tonsils of a 3 and a 11 years-old infants. The turnover time of lymphoid folliclesin nasal mucosa are so fast (about two weeks), then it is difficult to consider D-β-Asp proteins of lymphoid follicles are made during the long time exposure to UV, oxidant etc.

  The big difference to a staining pattern was not found in the palatine tonsils of a chronic tonsillitis and IgA nephropathy. From this point, D-β-Asp protein is not directly related to morbidity. Existence of D-β-Asp protein in lymphoid follicle of a child's palatine tonsil, and the D-β-Asp protein which is not directly related to morbidity was suggested.

It is the most important point to understand molecular mechanism how the fundamental life system, which is composed of gene, the genetic code and protein, was created, in order to solve the riddle on the origin of life. Thus far, several hypotheses, such as the space-origin hypothesis, the hydrothermal vent-origin hypothesis, junk world hypothesis and RNA world hypothesis, have been proposed to solve the riddle. But, all of them do not explain the mechanisms for creating gene, the genetic code, and protein. I suppose that the mechanisms cannot be explained by those hypotheses. On the other hand, [GADV]-protein world (the abbreviated form; GADV hypothesis), which I have proposed, may explain the molecular mechanisms without self-contradiction. In this review, I will explain strong points of the GADV hypothesis and processes for creation of gene, the genetic code and protein, and also describe necessary experiments to get evidence for establishment of the hypothesis.