Secondary and tertiary structure of pseudomurein

X-ray diffraction measurements and structural calculations on murein [22-25] and pseudomurein [26-28] have revealed several common structural features in both polymers. Murein and pseudomurein sacculi possess a density of p= 1. 39-1.46g/cm which is characteristic of highly ordered material. A much lower density, in the range of p= 1.24-1.32g/cm is to be expected for amorphous polymers [26]. X-ray diffraction showed diffuse Debye-Scherer rings with Bragg periodicities of about 0.45 nm and 0.94 nm in the planes and of 4.3-4.5nm vertically to the planes of both types of cell walls. These data have been interpreted in two different ways  

Information on lytic enzymes is still somewhat anecdotal. Methanobacterium biyantii undergoes spontaneous lysis when the or Ni ions are exhausted in the culture medium [30]. 

In the presence of o-sorbitol, Methanobacterium thermoautotrophicum forms protoplasts after addition of lysozyme to growing cells [31]. Growing cells of Methanobacterium thermoalcaliphilum were also found to lyse in the absence of substrate [32]. The mechanism responsible for the lysis has not been elucidated in any of these cases. An extracellular enzyme, produced by a streptomycete, was found to lyse Methanobacterium formicicum [33]. 

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