As problematical as the approach admittedly is, we must go back to the proteinaceous microspheres as possible protocells. We will approach them from the point of view of Oparin's coacervates, but adding that they contain uninformed proteins capable of some reflexive enzymatic activity. Enough has been said to show that such an approach is full of problems. But it is also clear why this seems to be the most promising approach. Frankly, at this point, we are speculating, but speculating within the rules of scientific inquiry; we are searching for testable explanations regarding the origin of life.
A coacervate containing reflexive enzymes can fulfill our definition of a living system. It could even be called an organism, since it could exploit its environment for the matter and energy to maintain itself. These would include spontaneously generated amino acids, nucleotides, sugar, and other organic compounds, including uninformed proteins, and as an energy source, heat or even possibly ATP. In the latter case one of the proteins might enzymatically split off the phosphate radicals and the released energy kept to help form more protein. This might or might not be part of the reflexive catalysis, but in any case, it contributes to formation of proteins making up the coacervate. Growth of the coacervate would come from the formation within it of various organic compounds, especially proteins. Large coacervates have been seen by Oparin and others to pinch in two when they reach a certain size. Apparently they are unstable above a certain size. This is growth and reproduction aided and abetted by the selective uptake of compounds and their enzymatically controlled reactions within the coacervate. Extensive study of coacervates as proteinoid microspheres as come from the laboratory of Sidney Fox and his colleagues at the Institute for Molecular and Cellular Evolution at the University of Miami. They have confirmed and greatly extended Oparin's initial ideas. Variations in these microspheres might come about through variations in the folding of the proteins.
Another source of variations has been suggested by the distinguished Japanese protein chemist Akabori. He proposed that proteins absorbed on clays could undergo reactions to amino acid side chains. This would change the sequence of the amino acids and change the conformations of the proteins, as well. This is a very important suggestion in three respects. First, it points to how an uninformed protein could take on the functions of an informed one, if side-chain substitutions led to enzymatic activity. Second, it could help explain how amino acids not arising spontaneously could become part of a protein with informed activities. And, third, instead of absorbing on clays, perhaps these early proteins absorbed on structures within the microspheres and there underwent side-chain substitutions. And their new properties could be immediately advantageous within microspheres.
If, and we repeat, if such microspheres arose they could be regarded as living. And because life would be associated with a discrete, three-dimensional structure--not a set of reactions in an organic soup--such a system would also be recognized as an organism.