Table 3.

List of amino acid residues of RBD of spike proteins of SARS-CoV-2 interacting with the cellular heparin sulfate proteoglycan (HSPG), and HSPG mimicking ligands (CMBS, PAS) classified based on the type of bonds formed.

Types of bonds	Amino acids interacting with heparin sulfate proteoglycan (HSPG)	Amino acids interacting with carboxymethyl benzyl amide sulfonate (CMBS)	Amino acids interacting with poly anethole sulfonic acid (PAS)
van der Waal’s Bond	Valine 433, Isoleucine 410, Lysine 378, Threonine 376, Valine 503, Proline 412, Glutamine 414, Glycine 404	Tyrosine 421, Arginine 457, Tyrosine 489, Phenylalanine 456, Tyrosine 453, Arginine 403, Tyrosine 495, Tyrosine 505, Serine 494	Glycine 431, Phenylalanine 429, Phenylalanine 515, Serine 514, Tyrosine 396, Arginine 355
Hydrogen Bond	Tyrosine 380, Tyrosine 508, Arginine 408	Tyrosine 473, Glutamine 493, Tyrosine 449, Glycine 496, Asparagine 501, Glutamine 498	Threonine 430
Amide- Pi Stacked Bond	Valine 407	–	–
Pi- Alkyl Bond	Alanine 411	Leucine 455, Alanine 475	Leucine 518, Proline 426
Pi-Cation Bond	–	Lysine 417	–
Pi-Anion Bond	–	–	Glutamic Acid 516