This is because their natural polymers have been stabilized by such helical structures. The figure below shows one such helical structure, called an a -helix . Small segments of such helical structures are what nature uses to mold enzymes into certain shapes so that they can do their catalytic magic. Enzymes Enzymes are one of the key types of polypeptides and are crucial to life on earth. All living organisms use enzymes to make, modify, and chop up the polymers discussed here.
Enzymes are the catalysts that do specific jobs.
In fact, oftentimes each enzyme does only one type of job or makes only one kind of molecule. This means that there have to be lots of different enzymes, all made of different combinations of amino acids joined in unique ways in polypeptides, to do all the jobs that any living organism needs done. We know that every creature on earth has hundreds or even thousands of different enzymes to do all the jobs that it requires. What's really strange is that each one of the enzymes has to be made by other enzymes. We are beginning to figure this out, and the study of such systems is an important part of biochemistry and biology.