Physiology, question coenzymes

It has been said that God created an organism especially adapted to help the biologist find an answer to every question about the physiology of living systems if this is so it must be concluded that pyridoxal phosphate was created to provide satisfaction and enlightenment to those enzymologists and chemists who enjoy pushing electrons, for no other coenzyme is involved in such a wide variety of reactions, in both enzyme and model systems, which can be reasonably interpreted in terms of the chemical properties of the coenzyme. Most of... 

In addition to the aspects mentioned above, the extent of PHA accumulation might depend on quite different features. The only physiological inhibitor of PHA synthase that has been identified is coenzyme A as pointed out in an earlier section. Since the concentration of coenzyme A in the cytoplasma will probably never rise to very high levels, it may be questionable whether this inhibition is physiologically relevant at all. In our opinion, the availability of a hy-droxyacyl coenzyme A thioester provided by the biosynthesis pathway is most important to initiate PHA biosynthesis (compare also [8] - this book). 

---