Using print and Internet resources, research a discovery of a structure in chemistry or biochemistry that depended heavily on model building.  Post an image of the model, along with a brief description of what the structure is, does, and where it's found on the forum - Structures in Chemistry and Biochemistry.

-Picture

• brief description of what structure is, does and where its found

 

Solution:

Several unforeseen and transforming developments appeared initially in the form of incremental advances, which in their aggregate led to new and more broadly based concepts in biochemistry, for example:

THE ALPHA HELIX:

THE DOUBLE HELIX:

THE PROTONMOTIVE FORCE:

ALLOSTERIC REGULATION:

COVALENT MODIFICATION OF ENZYMES:

SECOND MESSENGERS:

RIBOZYMES:

SITE?DIRECTED MUTAGENESIS:

THE EXPLOSIVE GROWTH IN COENZYMES:

TRANSITION STATE BINDING:

FREE RADICALS AS ENZYMATIC INTERMEDIATES:

LOW BARRIER HYDROGEN BONDS:

LOW BARRIER HYDROGEN BONDS: Where a low-barrier hydrogen bond (LBHB) is a special type of hydrogen bond, that occur when the pKa of the two heteroatoms are closely matched, which allows the hydrogen to be more equally shared between them, this hydrogen-sharing causes the formation of especially short, strong hydrogen bonds. Low barrier hydrogen bonds occur in the water-excluding environments of proteins. Multiple residues act together in a charge-relay system to control the pKa values of the residues involved. LBHBs also occur on the surfaces of proteins, but are unstable due to their proximity to bulk water, and the conflicting requirements of strong salt-bridges in protein-protein interfaces.

In the picture we can see that the Low barrier hydrogen bonds in transition state analogue complexes. At the top is the LBHB in the hemiketal complex of N?acetyl?l ?leucyl?l ?phenylalanine trifluoromethylketone with chymotrypsin. At the bottom is the LBHB in the complex of equilenin with Δ5?3?ketosteroid isomerase.

References:

https://iubmb.onlinelibrary.wiley.com/doi/full/10.1002/bmb.2002.494030030067

https://www.semanticscholar.org/paper/Direct-evidence-of-a-low-barrier-hydrogen-bond-in-a-Agback-Agback/5f49faf5b083aece27c2bf610603ee884302ee1c

https://en.wikipedia.org/wiki/Low-barrier_hydrogen_bond

https://www.nature.com/articles/s41586-019-1581-9

https://www.nature.com/articles/s41598-018-28441-7

PFA