Biotech mater­i­als made simple – crys­tal struc­tures altered by a single protein

In nacre, lay­er lat­tices of inor­gan­ic cal­ci­um car­bon­ate altern­ate with lay­ers of organ­ic mater­i­al. Chitin, col­la­gen and vari­ous pro­teins ensure that the cal­ci­um car­bon­ate grows in these defined lay­ers. What role the pro­teins play dur­ing growth had not pre­vi­ously been explained, but the assump­tion was that sev­er­al pro­teins acted togeth­er to con­trol the struc­ture of the cal­ci­um car­bon­ate lat­tice as well as them­selves form­ing part of the nacreous lay­ers. How­ever, Ingrid Weiss of the INM – Leib­n­iz Insti­tute for New Mater­i­als in Saar­brück­en and her col­league Boaz Pok­roy at the Tech­nion Israel Insti­tute of Tech­no­logy have now shown that the crys­tal lat­tice of cal­ci­um car­bon­ate can be altered using just a single pro­tein spe­cies. ​“This find­ing sim­pli­fies mat­ters and opens up new pos­sib­il­it­ies for indus­tri­al bio­tech­no­logy”, says Weiss, who is Head of the Bio­m­in­er­al­iz­a­tion Pro­gram at the INM. ​“Until now, indus­tri­al bio­tech­no­logy has labored under the idea that min­er­al­iz­a­tion could not be recre­ated using bio­lo­gic­al mod­els, because it was assumed that it took a com­bin­a­tion of sev­er­al pro­teins and a num­ber of factors that were not read­ily under­stand­able to make bio­m­in­er­al­iz­a­tion pos­sible”, she explains. If the nat­ur­al pro­cesses appeared too com­plic­ated, they would not be pur­sued in indus­tri­al devel­op­ment.

Pok­roy and Weiss have now proved that it need not to be that complicated:

In their exper­i­ments, the research­ers extrac­ted the pro­tein per­lu­cin from aba­lone (Hali­otis) shells and com­bined it with green fluor­es­cent pro­tein (GFP), a trick which enabled them to con­vert the insol­uble per­lu­cin to a water-sol­uble form. They added this solu­tion at dif­fer­ent con­cen­tra­tions to a cal­ci­um car­bon­ate solu­tion and examined the crys­tals pro­duced. The res­ults were com­pared to crys­tals pro­duced from a pure cal­ci­um car­bon­ate solu­tion and crys­tals pro­duced from a cal­ci­um car­bon­ate solu­tion with GFP. Only the dis­solved per­lu­cin was incor­por­ated in the inor­gan­ic car­bon­ate lat­tice, where it pro­duced not­able and wide-ran­ging dis­tor­tions to the lat­tice. The effect fol­lows a prin­ciple of ​“all or noth­ing”: small quant­it­ies of pro­tein are already enough to cause defined lat­tice dis­tor­tions. Once the dis­tor­tion starts, it then repro­duces itself con­tinu­ally across the lat­tice. ​“GFP alone simply coex­ists with cal­ci­um car­bon­ate – it sur­rounds the cal­ci­um car­bon­ate lat­tice like a jack­et without chan­ging it”, explains the bio­m­in­er­al­iz­a­tion expert. As in a shell, it seems to be the per­lu­cin that influ­ences the growth and struc­ture of the crys­tal lat­tice. To explain this phe­nomen­on, the research­ers used the INM’s expert­ise in mus­sel pro­teins and the expert­ise in crys­tal ana­lys­is at the Insti­tute in Haifa. This com­bin­a­tion made it pos­sible to observe the reac­tions of per­lu­cin in the crys­tal lat­tice. The sci­ent­ists are now keen to see wheth­er oth­er pro­teins have spe­cif­ic effects on the struc­ture and func­tion­al­ity of inor­gan­ic crys­tal lat­tices.

Ori­gin­al publication:

Eva Weber, Leonid Bloch, Christina Guth, Andy N. Fitch, Ingrid M. Weiss and Boaz Pok­roy; Chem. Mater., 2014, 26 (17), pp 4925 – 4932, DOI: 10.1021/cm500450s; http://​pubs​.acs​.org/​d​o​i​/​a​b​s​/​1​0​.​1​0​2​1​/​c​m​5​0​0450s

About INM

INM con­ducts research and devel­op­ment to cre­ate new mater­i­als – for today, tomor­row and bey­ond. Chem­ists, phys­i­cists, bio­lo­gists, mater­i­als sci­ent­ists and engin­eers team up to focus on these essen­tial ques­tions: Which mater­i­al prop­er­ties are new, how can they be invest­ig­ated and how can they be tailored for indus­tri­al applic­a­tions in the future? Four research thrusts determ­ine the cur­rent devel­op­ments at INM: New mater­i­als for energy applic­a­tion, new con­cepts for med­ic­al sur­faces, new sur­face mater­i­als for tri­bolo­gic­al sys­tems and nano safety and nano bio. Research at INM is per­formed in three fields: Nano­com­pos­ite Tech­no­logy, Inter­face Mater­i­als, and Bio Inter­faces. INM – Leib­n­iz Insti­tute for New Mater­i­als, situ­ated in Saar­brück­en, is an inter­na­tion­ally lead­ing centre for mater­i­als research. It is an insti­tute of the Leib­n­iz Asso­ci­ation and has about 195 employ­ees. Source: idw