Porphyran is the major polysaccharide of laver and mainly composed of 3-linked β-d-galactopyranose (G) and 4-linked α-l-galactopyranose-6-sulfate (L6S) units. Structural heterogeneity of porphyran highly originates from the natural methylation on the O-6 position of G units (GMe). Here, a GH16 porphyranase Por16C_Wf was cloned from a porphyran-related polysaccharide utilization locus of Wenyingzhuangia fucanilytica and expressed in Escherichia coli. It hydrolyzed porphyran in a random endo-acting manner. Using a glycomics strategy combining liquid chromatography–mass spectrometry and glycoinformatics, the subsite specificity was clarified. Por16C_Wf accommodated both G and GMe at subsites −1 and +2. This is the first report on the sequence of porphyranases hydrolyzing consecutive methyl-porphyranobiose moieties, which shed light on the diversity in subsite specificity of porphyranases. Por16C_Wf was the first characterized enzyme in subfamily 14 of the GH16 family. The defined and novel activity of Por16C_Wf implied that it could serve as a favorable tool in the full degradation and structural investigation of porphyran.

中文翻译：

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一种新型的卟啉酶在其亚位点容纳甲基半乳糖的表征。

紫菜是紫菜的主要多糖和主要由1,3-连接β- d -galactopyranose（G）和4-联α-升-galactopyranose -6-硫酸酯（L6S）单元。卟啉的结构异质性高度起源于G单元（GMe）O-6位置的天然甲基化。在这里，从文氏壮霉中的卟啉相关多糖利用位点克隆了GH16卟啉酶Por16C_Wf，并在大肠杆菌中表达。。它以随机的内在作用方式水解了卟啉。使用结合了液相色谱-质谱和糖信息学的糖组学策略，阐明了亚位特异性。Por16C_Wf在子站点-1和+2处同时容纳了G和GMe。这是关于卟啉酶水解连续的甲基-卟啉二糖部分的序列的第一份报道，这揭示了卟啉酶亚位特异性的多样性。Por16C_Wf是GH16家族亚家族14中第一个被表征的酶。Por16C_Wf的定义和新颖的活性暗示它可以作为卟啉的完全降解和结构研究的有利工具。