. Bioenergetics. Bioenergetics. '^\OAl. 1. The Problem Is Stated The problem is: how does energy drive life? How does it move the living machine? This is one of the most basic problems of biology and, at present, there is no answer to it. So it is possible that the "oscuro," alluded to in the Introduction, is due to our in- ability to answer this question. In order to avoid losing ourselves in generalities, we have to take a specific example. I will take a little experiment I made a few years ago. In this experiment I took a strip of muscle (I chose the musculus psoas of the rabbit),
. Bioenergetics. Bioenergetics. '^\OAl. 1. The Problem Is Stated The problem is: how does energy drive life? How does it move the living machine? This is one of the most basic problems of biology and, at present, there is no answer to it. So it is possible that the "oscuro," alluded to in the Introduction, is due to our in- ability to answer this question. In order to avoid losing ourselves in generalities, we have to take a specific example. I will take a little experiment I made a few years ago. In this experiment I took a strip of muscle (I chose the musculus psoas of the rabbit), put it into clUuted glycerol, and kept it in the glycerol for a few days in the refrigerator and for a few weeks in the deep freeze. Then I suspended it in Al KG at room temperature, added a little Mg, and added ATP in the same concentration as the muscle contained it in vivo. The muscle contracted and developed the same tension as it developed maxi- mally in the living animal. If we identify life with motion we could say: the muscle came to life again. In this process the ATP was split, losing its terminal phosphate which was linked to it by a P—O—P. Since we know that this link is a so-called high-energy phosphate bond, -^P, and no other energy donor was present, it is evident that the energy which moved the muscle was the energ)' of this '^P, and so we can narrow our problem down and ask how did the energy of the '^P move the muscle? Progress in the chemistry of muscle made it possible to simplify tl^ie problem even further. I showed almost two decades ago that contraction in muscle is, essentially, the interaction of actomyosin (a complex formed of two proteins, actin and myosin) with ATP and ions. Of the two proteins, myosin is responsible for the ele- mentary act of contraction and so we can simplify our proposition 3. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appear
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