Analysis of the binding specificity of <i>N</i>‐acetylgalactosamine (<scp>GalNAc</scp>)‐binding lectin isolated from <scp><i>Kappaphycus alvarezii</i></scp> to <scp>SARS</scp>‐<scp>CoV</scp>‐2 sugar moieties

SUMMARY N ‐acetylgalactosamine (GalNAc)‐binding lectin is one of the beneficial lectins because it has the ability to bind to glycoproteins or glycolipids containing GalNAc. Its potential applications include use as a drug delivery system, as well as for diagnostic tools and therapeutic interventions. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike proteins are known to be heavily glycosylated, and GalNAc‐binding lectin can potentially bind with these glycoproteins. The present study specifically investigated the interactions between GalNAc‐binding lectin from Kappaphycus alvarezii (Rhodophyta) and the sugars and glycoproteins present on the S protein of the SARS‐CoV‐2 virus. The GalNAc‐specific lectin was successfully isolated from K. alvarezii var. tangan‐tangan (Loving Beauty) and purified using a Sepharose 6B‐GalNAc affinity column. This lectin demonstrated stability within the temperature range 30–80°C and pH range 3–9. The minimum inhibitory concentration of this lectin was determined to be 0.001 mg mL −1 . Sugar specificity tests confirmed its ability to bind to the sugars and glycoproteins reported to be present on the S protein of the SARS‐CoV‐2 virus envelope. These results suggest that the potential of GalNAc‐specific lectin from K. alvarezii can be further explored, making it a promising candidate for therapeutic interventions against coronavirus.