The renin-angiotensin-aldosterone system (RAAS) is an intricate physiological pathway involving numerous enzymes and hormones, including renin, angiotensin-converting enzyme (ACE), angiotensin I and II, and aldosterone. Imbalances within this system increase the production of angiotensin II and aldosterone. Increased angiotensin II levels promote vasoconstriction and blood pressure elevation. Concurrently, higher aldosterone levels stimulate sodium and water reabsorption in the kidneys,...

Biochemical reactions are occurring constantly in cells, converting starting substances to different products, usually with the help of enzymes that speed the reactions. Without enzymes, it would take far too long for most reactions to occur to be useful to the cell!

Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.

Rapid Amplification of cDNA Ends, or RACE, is one of the most effective methods to obtain a full-length cDNA from an mRNA sequence between a known internal region to the unknown sequence at the 5’ or 3’ end. The unknown region is cloned in the cDNA by a gene-specific primer that binds the known end, and a hybrid primer that attaches a predefined anchor sequence to the unknown end of the cDNA. The sequence in between is amplified by PCR with an anchor primer and a gene-specific...

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...

In most cases, excessive hormone production is prevented by negative feedback—a loop that starts with a stimulus inducing the release of a particular substance, like a hormone, to maintain a certain level before triggering a signal that results in a decrease in further release of the hormone.