11:45 〜 12:00
[U08-08] 一般的な化学反応ネットワークにおける自己触媒増幅率の予測
キーワード：自己触媒、応用数理、生命起源、初期代謝
Autocatalysis is at the core of biological replication. The synthesis of new DNA is an autocatalytic cycle which doubles the amount of DNA per biosynthesis cycle (DNA -> DNA). Reproduction of unicellular organism is also autocatalytic, with the amplification factor depending on external factors such as the temperature or chemicals contained in the growth media (cell -> cells). Sexual reproduction can also be autocatalytic in the sense that a population starting from one male and one female may grow exponentially over time. However, compared to the previous examples, this is a more complex autocatalytic network because two initial components (male + female) are necessary, not one (DNA, unicellular organism).
Autocatalytic systems which cannot be written in the scheme (X -> X) fall outside the traditional definitions of autocatalysis in chemistry, and have been understudied so far. On the other hand, autocatalysis is almost never truly a single step reaction, such as in all of the examples shown above. Multiple chemical reactions and chemical species must be combined to realize autocatalytic function, as a system commonly referred to as “network autocatalysis”.
Some specific combinations of chemical reactions, such as the reverse tricarboxylic acid (rTCA) cycle, have been proposed to be the origin of metabolism due to their autocatalytic nature as a network. However, while these reactions are known to proceed in the presence of enzymes, the possibility of autocatalysis without selective catalysts remains unclear. In particular, how promiscuous or selective each reaction must be to realize autocatalysis (amplification factor > 1) is missing.
Here, we provide a theoretical framework to assess the relationship between the selectivity of each reaction and the amplification factor for a general network containing N species. During the presentation, the mathematical assumptions leading to the final formula will be discussed.
Autocatalytic systems which cannot be written in the scheme (X -> X) fall outside the traditional definitions of autocatalysis in chemistry, and have been understudied so far. On the other hand, autocatalysis is almost never truly a single step reaction, such as in all of the examples shown above. Multiple chemical reactions and chemical species must be combined to realize autocatalytic function, as a system commonly referred to as “network autocatalysis”.
Some specific combinations of chemical reactions, such as the reverse tricarboxylic acid (rTCA) cycle, have been proposed to be the origin of metabolism due to their autocatalytic nature as a network. However, while these reactions are known to proceed in the presence of enzymes, the possibility of autocatalysis without selective catalysts remains unclear. In particular, how promiscuous or selective each reaction must be to realize autocatalysis (amplification factor > 1) is missing.
Here, we provide a theoretical framework to assess the relationship between the selectivity of each reaction and the amplification factor for a general network containing N species. During the presentation, the mathematical assumptions leading to the final formula will be discussed.