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| [credit by Peter Allen] |
Humans can smell with his nose, humans are able to do that because of the protein in the body. Proteins are made up of long chains of amino acids. These proteins are assembled in the human body very quickly, even in milliseconds. To understand how these proteins are assembled, we should be able to see the process. Scientists from the University of Montreal had watched with a new approach. The results of this study is very useful in understanding Alzheimer's and Parkinson's disease.
Strategies developed by these researchers is to integrate the fluorescent probes throughout the protein chain linear so that we could detect the protein structure of each stage, step by step for the assembly of the final structure. NMR or X-ray crystallography can not be directly applied to observe the process of protein assembly. The scientists showed that transient states during protein folding can be characterized by measuring the fluorescence of tryptophan residues, introduced at many solvent-exposed positions to determine whether each position is native-like, denatured-like or non-native-like in the intermediate state.
“In order to survive, all creatures, from bacteria to humans, monitor and transform their environments using small protein nanomachines made of thousands of atoms,” explained the senior author of the study, Prof. Stephen Michnick of the university’s department of biochemistry. “For example, in our sinuses, there are complex receptor proteins that are activated in the presence of different odor molecules. Some of those scents warn us of danger; others tell us that food is nearby.” Proteins are made of long linear chains of amino acids, which have evolved over millions of years to self-assemble extremely rapidly – often within thousandths of a split second - into a working nanomachine. “One of the main challenges for biochemists is to understand how these linear chains assemble into their correct structure given an astronomically large number of other possible forms,” Michnick said.
“To understand how a protein goes from a linear chain to a unique assembled structure, we need to capture snapshots of its shape at each stage of assembly said Dr. Alexis Vallée-Bélisle, first author of the study. “The problem is that each step exists for a fleetingly short time and no available technique enables us to obtain precise structural information on these states within such a small time frame. We developed a strategy to monitor protein assembly by integrating fluorescent probes throughout the linear protein chain so that we could detect the structure of each stage of protein assembly, step by step to its final structure.” The protein assembly process is not the end of its journey, as a protein can change, through chemical modifications or with age, to take on different forms and functions. “Understanding how a protein goes from being one thing to becoming another is the first step towards understanding and designing protein nanomachines for biotechnologies such as medical and environmental diagnostic sensors, drug synthesis of delivery,” Vallée-Bélisle said.
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