Glycoproteins isolation from natural sources

The main drawback of glycoprotein isolation and extraction from natural sources is the complexity of purification arising from their expression as mixtures of different glycoforms [6], These protein isoforms differ only with respect to the number, type of attached gly cans, or gly cosy lation site yet may result in many hundreds of variants. Homogeneous glycoforms cannot be readily accessed from natural sources because glycosylation, as with other posttranslational modifications, is not directly genetically driven. 

Although capable of glycosylating heterologous human proteins, the glycosylation pattern usually varies from the pattern observed on the native glycoprotein (when isolated from its natural source, or when expressed in recombinant animal cell culture systems). 

Other natural sources of anti-HSV PS include fungi, e g., various protein bound PS isolated from Ganoderma lucidum, a basidiomycetous fungus used to treat human diseases in oriental folk medicine [98], The possible mode of antiviral activity of these PS seems to be related to their binding with HSV-specific glycoproteins responsible for attachment and... 

Commercially available a-amylase (Sigma) or Taka-diastase (Sankyo) is an enzyme mixture from the fungus A. oryzae, and it has been a convenient source for the isolation of RNase Tl. Note that Taka-diastase also contains nuclease SI (Section IV,A this chapter) and another, less abundant RNase T2. The RNase T2 is a glycoprotein similar to RNase Tl, but it has a higher MW (29,000), a pi of 5.0, and, most notably, no absolute base specificity. In nature, RNase Tl is an extracellular enzyme, similar to guanylo-RNases from various other bacterial and fungal organisms. 

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