Endo-beta-N-acetylglucosaminidaseF1（EndoF1） is an endoglyco-sidasee, secreted by Elizabethkingia meningoseptica, that cleaves aspa-raginelinked oligosaccharides after the first N-acetylglucosamine residue. The enzyme is selective for high-mannose oligosaccharide chains. Glycosylation of the core fucoidan of the heterodimeric structure reduces the cleavage rate of EndoF1 by more than EndoF1 hydrolyzes sulfate containing high mannose chains. EndoF1 can be used under natural or non-denatured deglycosylation conditions. The enzyme is suitable for deglycosylation of glycoproteins under natural conditions and is suitable for a variety of glycomics applications, proteomics and mass spectrometry applications.