Extracting and combination efficient feature from protein sequence for classify protein based on rotation forest

Protein function prediction is one of the main challenges in bioinformatics, which has many applications. In recent years, many researches in this field have been used machine learning methods. In these methods, First, different features should be extracted from the protein sequence and classification should be done based on the extracted features. The feature extraction methods are based on the physical and chemical properties of the protein sequence. Therefore, extracting suitable features from protein sequence increases and improves the performance of machine learning methods. In this paper, usage of a new set of features based on Position-Specific Scoring Matrix (PSSM), Pseudo-Position Specific Scoring Matrix (PsePSSM), K-gram, Amino Acid Composition (AAC) and the new Term Frequency and Category Relevancy Factor (TFCRF) method, which has not been used in this application so far, is proposed to extract suitable features. In the PSSM method for protein BLAST searches, a scoring matrix is used, in which amino acid substitution scores are given separately for each position in a multi-sequence protein alignment. The PsePSSM feature is described by considering different ranking correlation factors along a protein sequenc to preserve information about the amino acid sequence. The normalized occurrence frequency of a certain number of amino acids in the protein is calculated by the ACC method. An K-gram is a set of K successive items in a protein that  include amino acid. In the TFCRF weighting method, in addition to paying attention to how these are distributed in different sequences, how these are distributed in different classes is also paid attention to.The features extracted using this method give machine learning models a good discriminating power between data in classes. In the next step, classification is done using the extracted features using the rotation forest method. This classifier is a successful ensemble method for a wide range of data mining applications. In this method, the feature space is changed through Principal Component Analysis (PCA), which increases the power of this classifier. The proposed method has been compared to different classifiers. The results show that the efficiency of the proposed method is much better than other state-of–the-art methods in this application.