J Basic Microbiol. 2019;1–10. www.jbm-journal.com © 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim | 1 Received: 29 July 2019 | Revised: 14 September 2019 | Accepted: 29 September 2019 DOI: 10.1002/jobm.201900428 RESEARCH PAPER Purification of a potent mitogenic homodimeric Penicillium griseoroseum lectin and its characterisation Ram S. Singh | Amandeep K. Walia Carbohydrate and Protein Biotechnology Laboratory, Department of Biotechnology, Punjabi University, Patiala, India Correspondence Ram Sarup Singh, Carbohydrate and Protein Biotechnology Laboratory, Department of Biotechnology, Punjabi University, Patiala, Punjab 147002, India. Email: rssbt@pbi.ac.in and rssinghpta@gmail.com Abstract Penicillium griseoroseum lectin was 80‐fold purified by successive DEAE Sepharose anion exchange and Sephadex G‐100 gel permeation chromatogra- phy. P. griseoroseum lectin exhibited haemagglutination activity towards protease‐treated rabbit erythrocytes. It showed specificity towards various carbohydrates such as D‐mannose, N‐acetyl‐D‐glucosamine, mucins, and so forth. P. griseoroseum lectin was found as a glycoprotein with glycan content of 4.33%. Purified P. griseoroseum lectin is homodimeric having a molecular mass of 57 kDa with subunit molecular mass of 28.6 kDa. Haemagglutination activity of purified P. griseoroseum lectin was completely stable from 25°C to 35°C at a pH range of 6–7.5. Lectin activity was not influenced by divalent metal ions and denaturants. P. griseoroseum lectin manifested mitogenicity towards mice splenocytes and activity reached a peak at 75 μg/ml of lectin concentration. P. griseoroseum lectin in microgram concentrations stimulated proliferation of mice splenocytes. Thus, P. griseoroseum lectin exhibits potential mitogenicity, which can be exploited for further biomedical applications. KEYWORDS haemagglutination, lectin, mitogenicity, Penicillium griseoroseum 1 | INTRODUCTION Lectins are heterogenous group of glycan‐binding proteins/glycoproteins of nonimmunogenic origin. They bind reversibly and specifically to cell surface glycans at two or more binding sites [1]. These noncatalytic (glyco)proteins possess atleast one carbo- hydrate recognition domain (CRD), which interacts with glycans without modifying their covalent struc- ture [2]. These CRDs of lectins specifically interact with glycans, which establishes the notion of protein–- carbohydrate recognition. Lectin–carbohydrate inter- actions have been involved in various biological functions and thus widely utilised in biomedical arena including cellular biology, biochemical, and immuno- logical studies [3]. Lectins are ubiquitous in plants, animals, and microorganisms [4]. Several studies have been carried out on algae [5–7], lichens [8], protozoa [9,10], mushrooms [11,12], yeasts [13], microfungi [14], and so forth, revealing their importance as a potential source of lectins. Lectins from various microfungal species have been explored, including Aspergillus sp. [15–18], Cephalosporium sp. [18,19], Fusarium sp. [20–23], Penicillium sp. [24–27], Rhizoc- tania sp. [28,29], Sclerotium sp. [30], and so forth. Microfungal lectins mediate many biological processes and can play significant role in microbial adhesion to host cells, a prerequisite for infection to occur [31]. Microfungal lectins have evoked considerable interest as biomarkers in cancer therapy [29] and have also been explored as modulators of immune response for ther- apeutic purposes [32–34]. They also exhibit diverse applications including antimicrobial activity [26,35,36], anti‐insecticide [24], antioxidant [37], and so forth.