Wikipedia
DSSP may refer to:
- DSSP (programming), a programming language, acronym for Dialog System for Structured Programming
- DSSP (imaging), a method of scanning objects into 3D digital representations
- DSSP (hydrogen bond estimation algorithm), an algorithm that determines the secondary structure of protein subsequences from the coordinates of a protein structure
- Decentralized Software Services Protocol, a SOAP-based protocol used by Microsoft Robotics Developer Studio
- Deep Submergence Systems Project, US Navy program to develop methods of rescuing submarines
- Dessert spoon, a spoon with a capacity of about 2 teaspoons
- Digital Solid State Propulsion, USA-based aerospace company.
DSSP stands for digital shape sampling and processing. It is an alternative and often preferred way of describing " reverse engineering" software and hardware. The term originated in a 2005 Society of Manufacturing Engineers' "Blue Book" on the topic, which referenced numerous suppliers of both scanning hardware and processing software.
DSSP employs various 3D scanning methods, including laser scanners, to acquire thousands to millions of points on the surface of a form and then software from a variety of suppliers to convert the resulting " point cloud" into forms useful for inspection, computer-aided design, visualization and other applications. It may also employ volumetric methods of scanning, such as digital tomography.
Some common applications include CAI (computer-aided inspection), creation of 3D CAD models from scanned data, medical applications, 3D imaging for Web 2.0 applications, and the restoration of culturally significant artifacts; as well as conventional reverse engineering for creating replacement parts.
The term 'reverse engineering' itself has acquired some notoriety when the technology has been used to copy others' designs.
The term 'laser scanning' has also been used somewhat interchangeably for DSSP. However, there are two problems with the term as a broad description of the field. First, it is only one of many alternative scanning technologies. Second, it misses the essential role of processing software in converting point cloud data into useful forms.
In some ways, DSSP is a 3D analog to DSP ( digital signal processing) in that the software attempts to extract a clear and accurate 3D image from point data that may include noise. The notion of 'shape sampling' embedded in the term also acknowledges that, as in many measurement processes, the accuracy of the 3D data will depend upon the number and accuracy of points sampled.
The speed and accuracy of both scanners to acquire data and software algorithms to extract useful data has dramatically increased in recent years. The amount of data capturing capability has also increased many fold, due to the advances in the camera technology and faster , more powerful computers. As some the limitations of the technology are eliminated and costs reduced, more uses are appearing.
The DSSP algorithm is the standard method for assigning secondary structure to the amino acids of a protein, given the atomic-resolution coordinates of the protein. The abbreviation is only mentioned once in the 1983 paper describing this algorithm, where it is the name of the Pascal program that implements the algorithm Define Secondary Structure of Proteins.
DSSP begins by identifying the intra-backbone hydrogen bonds of the protein using a purely electrostatic definition, assuming partial charges of -0.42 e and +0.20 e to the carbonyl oxygen and amide hydrogen respectively, their opposites assigned to the carbonyl carbon and amide nitrogen. A hydrogen bond is identified if E in the following equation is less than -0.5 kcal/mol:
$$E = 0.084 \left\{ \frac{1}{r_{ON}} + \frac{1}{r_{CH}} - \frac{1}{r_{OH}} - \frac{1}{r_{CN}} \right\} \cdot 332 \, \mathrm{kcal/mol}$$
Based on this, eight types of secondary structure are assigned. The 3 helix, α helix and π helix have symbols G, H and I and are recognized by having a repetitive sequence of hydrogen bonds in which the residues are three, four, or five residues apart respectively. Two types of beta sheet structures exist; a beta bridge has symbol B while longer sets of hydrogen bonds and beta bulges have symbol E. T is used for turns, featuring hydrogen bonds typical of helices, S is used for regions of high curvature (where the angle between $\overrightarrow{C_i^\alpha C_{i+2}^\alpha}$ and $\overrightarrow{C_{i-2}^\alpha C_i^\alpha}$ is less than 70°), and a blank (or space) is used if no other rule applies, referring to loops. These eight types are usually grouped into three larger classes: helix (G, H and I), strand (E and B) and loop (S, T, and C, where C sometimes is represented also as blank space).
In 2002, a continuous DSSP assignment was developed by introducing multiple hydrogen bond thresholds, where the new assignment was found to correlate with protein motion.