Angiotensin II

 Application of Stereochemistry in the RAAS System

Introduction

First formally recognized by scientists at the turn of the 20^th century, the Renin-angiotensin-aldosterone system is arguably one of them most important neuroendocrine networks in the human body. From regulating blood sodium concentrations and blood pressure in the cardiovascular and urinary systems to stimulating areas of the brain that facilitate respiratory functioning, this system is one of several homeostatic control mechanisms that help keep us alive.

Charged with the task of examining the role that stereochemistry might have in nature for this month’s blog topic, 

I was interested to learn about the impact stereochemistry has upon the RAS system.

Angiotensin II and Role in RAAS

Produced by angiotensin convertingenzyme (ACE) in the capillary endothelium of the human body, angiotensin II is the final neuroendocrine hormone in the renin-angiotensin-aldosterone hormonal mechanism that  targets a variety of receptors responsible for initiating such physiological functions as vasodilation and sodium reabsorption in the kidney tubules. 

Chemical Structure and Stereochemistry of Angiotensin II

A member of the octapeptide class of proteins, angiotensin II's chemical structure is comprised of eight amino acids that are each in an levo-rotatory enantiomer configuration (L-α-Aspartyl-L-arginyl-L-valyl-L-tyrosyl-L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanine).

Angiotensin II has 9 chiral centers.

    

To appreciate the complexity of the 

3 dimensional structure, I've included the following  screenshot taken in the computer program Jmol.