Final answer:
Structure-Activity Relationship (SAR) studies on cardioactive glycosides involve systematic molecule modifications to elucidate how changes affect binding affinity and biological activity, ultimately optimizing the compounds for therapeutic use.
Step-by-step explanation:
The concept of Structure-Activity Relationship (SAR) is crucial in understanding how modifications in the molecular structure of substances can affect their biological activity. In the context of cardioactive glycosides, SAR investigations would typically involve modifications of the glycoside molecule to determine how changes influence binding affinity and biological function. This usually involves a systematic approach of amino acid scans, terminal modifications, and truncation to isolate the minimal active sequence necessary for the desired activity.
For example, analogs of the peptides or glycosides may be created where each amino acid or moiety is replaced by a minimal residue like alanine or glycine, and the results are compared to the original molecule's biological activity. N- or C-terminal modifications can reveal the importance of these regions, while truncation studies can identify the shortest effective sequence. Collectively, these studies enable researchers to pinpoint essential residues and pharmacophoric groups for biological activity, allowing further optimization for increased stability, potency, and selectivity of the cardioactive agent.